MDEV-4425 REGEXP enhancements

Adding pcre_stack_guard to avoid crashes in pcre_compile()
on a long recursive patterns with parenthesizes:

SELECT a RLIKE '((((...((((x)))...))))';

1 files changed, 6 insertions, 0 deletions

diff --git a/pcre/pcre_compile.c b/pcre/pcre_compile.c
index 1f7bdb40b19..0ebb3f168f1 100644
--- a/pcre/pcre_compile.c
+++ b/pcre/pcre_compile.c
@@ -7107,6 +7107,12 @@ unsigned int orig_bracount;
 unsigned int max_bracount;
 branch_chain bc;
 
+if (pcre_stack_guard && pcre_stack_guard())
+{
+  *errorcodeptr= ERR23;
+  return FALSE;
+}
+ 
 bc.outer = bcptr;
 bc.current_branch = code;