CLEANUP: config: make the cfg_keyword parsers take a const for the defproxy

The default proxy was passed as a variable to all parsers instead of a
const, which is not without risk, especially when some timeout parsers used
to make some int pointers point to the default values for comparisons. We
want to be certain that none of these parsers will modify the defaults
sections by accident, so it's important to mark this proxy as const.

This patch touches all occurrences found (89).
diff --git a/src/hlua.c b/src/hlua.c
index 12a4872..42d5be2 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -8132,7 +8132,7 @@
 }
 
 static int hlua_read_timeout(char **args, int section_type, struct proxy *curpx,
-                             struct proxy *defpx, const char *file, int line,
+                             const struct proxy *defpx, const char *file, int line,
                              char **err, unsigned int *timeout)
 {
 	const char *error;
@@ -8156,7 +8156,7 @@
 }
 
 static int hlua_session_timeout(char **args, int section_type, struct proxy *curpx,
-                                struct proxy *defpx, const char *file, int line,
+                                const struct proxy *defpx, const char *file, int line,
                                 char **err)
 {
 	return hlua_read_timeout(args, section_type, curpx, defpx,
@@ -8164,7 +8164,7 @@
 }
 
 static int hlua_task_timeout(char **args, int section_type, struct proxy *curpx,
-                             struct proxy *defpx, const char *file, int line,
+                             const struct proxy *defpx, const char *file, int line,
                              char **err)
 {
 	return hlua_read_timeout(args, section_type, curpx, defpx,
@@ -8172,7 +8172,7 @@
 }
 
 static int hlua_applet_timeout(char **args, int section_type, struct proxy *curpx,
-                               struct proxy *defpx, const char *file, int line,
+                               const struct proxy *defpx, const char *file, int line,
                                char **err)
 {
 	return hlua_read_timeout(args, section_type, curpx, defpx,
@@ -8180,7 +8180,7 @@
 }
 
 static int hlua_forced_yield(char **args, int section_type, struct proxy *curpx,
-                             struct proxy *defpx, const char *file, int line,
+                             const struct proxy *defpx, const char *file, int line,
                              char **err)
 {
 	char *error;
@@ -8194,7 +8194,7 @@
 }
 
 static int hlua_parse_maxmem(char **args, int section_type, struct proxy *curpx,
-                             struct proxy *defpx, const char *file, int line,
+                             const struct proxy *defpx, const char *file, int line,
                              char **err)
 {
 	char *error;
@@ -8270,7 +8270,7 @@
 }
 
 static int hlua_load(char **args, int section_type, struct proxy *curpx,
-                     struct proxy *defpx, const char *file, int line,
+                     const struct proxy *defpx, const char *file, int line,
                      char **err)
 {
 	if (*(args[1]) == 0) {
@@ -8285,7 +8285,7 @@
 }
 
 static int hlua_load_per_thread(char **args, int section_type, struct proxy *curpx,
-                                struct proxy *defpx, const char *file, int line,
+                                const struct proxy *defpx, const char *file, int line,
                                 char **err)
 {
 	int len;
@@ -8345,7 +8345,7 @@
 }
 
 static int hlua_config_prepend_path(char **args, int section_type, struct proxy *curpx,
-                                    struct proxy *defpx, const char *file, int line,
+                                    const struct proxy *defpx, const char *file, int line,
                                     char **err)
 {
 	char *path;