BUG/MINOR: tcpcheck: proxy_parse_*check*() must take a const for the defproxy

The default proxy was passed as a variable, which in addition to being
a PITA to deal with in the config parser, doesn't feel safe to use when
it ought to be const.

This will only affect new code so no backport is needed.
diff --git a/include/haproxy/tcpcheck.h b/include/haproxy/tcpcheck.h
index 29b4c9b..40005a2 100644
--- a/include/haproxy/tcpcheck.h
+++ b/include/haproxy/tcpcheck.h
@@ -83,23 +83,23 @@
                                             struct list *rules, unsigned int proto,
                                             const char *file, int line, char **errmsg);
 
-int proxy_parse_tcp_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_tcp_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			      const char *file, int line);
-int proxy_parse_redis_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_redis_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 				const char *file, int line);
-int proxy_parse_ssl_hello_chk_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_ssl_hello_chk_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 				  const char *file, int line);
-int proxy_parse_smtpchk_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_smtpchk_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			const char *file, int line);
-int proxy_parse_pgsql_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_pgsql_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 				const char *file, int line);
-int proxy_parse_mysql_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_mysql_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			    const char *file, int line);
-int proxy_parse_ldap_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_ldap_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			       const char *file, int line);
-int proxy_parse_spop_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_spop_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			       const char *file, int line);
-int proxy_parse_httpchk_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_httpchk_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			    const char *file, int line);
 
 
diff --git a/src/tcpcheck.c b/src/tcpcheck.c
index 94ba28f..100c727 100644
--- a/src/tcpcheck.c
+++ b/src/tcpcheck.c
@@ -3872,7 +3872,7 @@
 }
 
 /* Parses the "option redis-check" proxy keyword */
-int proxy_parse_redis_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_redis_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 				const char *file, int line)
 {
 	static char *redis_req = "*1\r\n$4\r\nPING\r\n";
@@ -3946,7 +3946,7 @@
 
 
 /* Parses the "option ssl-hello-chk" proxy keyword */
-int proxy_parse_ssl_hello_chk_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_ssl_hello_chk_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 				  const char *file, int line)
 {
 	/* This is the SSLv3 CLIENT HELLO packet used in conjunction with the
@@ -4045,7 +4045,7 @@
 }
 
 /* Parses the "option smtpchk" proxy keyword */
-int proxy_parse_smtpchk_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_smtpchk_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			    const char *file, int line)
 {
 	static char *smtp_req = "%[var(check.smtp_cmd)]\r\n";
@@ -4186,7 +4186,7 @@
 }
 
 /* Parses the "option pgsql-check" proxy keyword */
-int proxy_parse_pgsql_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_pgsql_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 				const char *file, int line)
 {
 	static char pgsql_req[] = {
@@ -4333,7 +4333,7 @@
 
 
 /* Parses the "option mysql-check" proxy keyword */
-int proxy_parse_mysql_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_mysql_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 				const char *file, int line)
 {
 	/* This is an example of a MySQL >=4.0 client Authentication packet kindly provided by Cyril Bonte.
@@ -4556,7 +4556,7 @@
 	goto out;
 }
 
-int proxy_parse_ldap_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_ldap_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			       const char *file, int line)
 {
 	static char *ldap_req = "300C020101600702010304008000";
@@ -4636,7 +4636,7 @@
 	goto out;
 }
 
-int proxy_parse_spop_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_spop_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			       const char *file, int line)
 {
 	struct tcpcheck_ruleset *rs = NULL;
@@ -4841,7 +4841,7 @@
 }
 
 /* Parses the "option httpchck" proxy keyword */
-int proxy_parse_httpchk_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_httpchk_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			    const char *file, int line)
 {
 	struct tcpcheck_ruleset *rs = NULL;
@@ -4911,7 +4911,7 @@
 }
 
 /* Parses the "option tcp-check" proxy keyword */
-int proxy_parse_tcp_check_opt(char **args, int cur_arg, struct proxy *curpx, struct proxy *defpx,
+int proxy_parse_tcp_check_opt(char **args, int cur_arg, struct proxy *curpx, const struct proxy *defpx,
 			      const char *file, int line)
 {
 	struct tcpcheck_ruleset *rs = NULL;