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/haproxy.c b/src/haproxy.c
index cd42b34..9f742c7 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1034,8 +1034,8 @@
 
 		for (exp = p->req_exp; exp != NULL; ) {
 			if (exp->preg) {
-				regfree((regex_t *)exp->preg);
-				free((regex_t *)exp->preg);
+				regex_free(exp->preg);
+				free(exp->preg);
 			}
 
 			if (exp->replace && exp->action != ACT_SETBE)
@@ -1047,8 +1047,8 @@
 
 		for (exp = p->rsp_exp; exp != NULL; ) {
 			if (exp->preg) {
-				regfree((regex_t *)exp->preg);
-				free((regex_t *)exp->preg);
+				regex_free(exp->preg);
+				free(exp->preg);
 			}
 
 			if (exp->replace && exp->action != ACT_SETBE)