MINOR: init: make -cc support environment variables expansion

I found myself a few times testing some conditoin examples from the doc
against command line's "-cc" to see that they didn't work with environment
variables expansion. Not being documented as being on purpose it looks like
a miss, so let's add PARSE_OPT_ENV and PARSE_OPT_WORD_EXPAND to be able to
test for example -cc "streq(${WITH_SSL},yes)" to help debug expressions.
diff --git a/src/haproxy.c b/src/haproxy.c
index 8a9f50c..2d32bb8 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1808,7 +1808,7 @@
 		size_t outlen = strlen(check_condition) + 1;
 
 		err = parse_line(check_condition, check_condition, &outlen, args, &arg,
-		                 PARSE_OPT_DQUOTE | PARSE_OPT_SQUOTE | PARSE_OPT_BKSLASH,
+		                 PARSE_OPT_ENV | PARSE_OPT_WORD_EXPAND | PARSE_OPT_DQUOTE | PARSE_OPT_SQUOTE | PARSE_OPT_BKSLASH,
 		                 &errptr);
 
 		if (err & PARSE_ERR_QUOTE) {