core: Fix a memory leak in app.c from an early return

ast_app_group_match_get_count allocates memory with the regcomp
function and we previously forgot to free it when bailing out
due to a regex compilation failure against category.

(closes issue AST-1018)
Reported by: Guenther Kelleter
Patches:
	regcomp_memleak.diff uploaded by Guenther Kelleter (license 6372)
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Merged revisions 375299 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 375300 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@375301 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/app.c

@@ -1562,6 +1562,7 @@ int ast_app_group_match_get_count(const char *groupmatch, const char *category)
 
 	if (!ast_strlen_zero(category) && regcomp(&regexbuf_category, category, REG_EXTENDED | REG_NOSUB)) {
 		ast_log(LOG_ERROR, "Regex compile failed on: %s\n", category);
+		regfree(&regexbuf_group);
 		return 0;
 	}