MDEV-9577: sys_vars.ignore_db_dirs_basic fails under Valgrind

Ensure that the command line argument is of sufficient length before moving past the leading long option marker "--".

Author: Nirbhay Choubey

sql/wsrep_check_opts.cc

@@ -151,7 +151,20 @@ find_opts (argv_copy& a, struct opt* const opts)
 {
  for (int i = 0; i < a.argc_; ++i)
  {
- char* ptr = a.argv_[i] + 2; // we're interested only in long options
+ char *ptr;
+
+ /*
+ We're interested only in long options, ensure that the arg is of
+ sufficient length.
+ */
+ if (strlen(a.argv_[i]) > 2)
+ {
+ ptr= a.argv_[i] + 2;
+ }
+ else
+ {
+ continue;
+ }
 
  struct opt* opt = opts;
  for (; 0 != opt->name; ++opt)