MEDIUM: regex: replace all standard regex function by own functions

This patch remove all references of standard regex in haproxy. The last
remaining references are only in the regex.[ch] files.

In the file src/checks.c, the original function uses a "pmatch" array.
In fact this array is unused. This patch remove it.
diff --git a/src/regex.c b/src/regex.c
index 8de56e6..2292002 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -124,7 +124,7 @@
 
 
 /* returns the pointer to an error in the replacement string, or NULL if OK */
-const char *chain_regex(struct hdr_exp **head, const regex_t *preg,
+const char *chain_regex(struct hdr_exp **head, struct my_regex *preg,
 			int action, const char *replace, void *cond)
 {
 	struct hdr_exp *exp;