MEDIUM: pattern: Extract the index process from the pat_parse_*() functions

Now, the pat_parse_*() functions parses the incoming data. The input
"pattern" struct can be preallocated. If the parser needs to add some
buffers, it allocates memory.

The function pattern_register() runs the call to the parser, process
the key indexation and associate the "sample_storage" used by maps.
diff --git a/src/proto_http.c b/src/proto_http.c
index 41561c5..2ce0d33 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -8735,14 +8735,13 @@
  * We use the pre-parsed method if it is known, and store its number as an
  * integer. If it is unknown, we use the pointer and the length.
  */
-static int pat_parse_meth(const char **text, struct pattern *pattern, struct sample_storage *smp, int *opaque, char **err)
+static int pat_parse_meth(const char **text, struct pattern *pattern, int *opaque, char **err)
 {
 	int len, meth;
 
 	len  = strlen(*text);
 	meth = find_http_meth(*text, len);
 
-	pattern->smp = smp;
 	pattern->val.i = meth;
 	if (meth == HTTP_METH_OTHER) {
 		pattern->ptr.str = strdup(*text);