smartmatch reset issue

[atoomic]

This is a simplified version of xtestc/0274.t which is failing due to reset not working for a smartmatch

other tests impacted by this case:

• xtestc/0274.t
• op/reset.t

sub match { shift =~ m?xyz? ? 1 : 0; }

print "1..4\n";
print "ok 1 - first match succeeds\n" if match("xyz");
print "ok 2 - second match fails\n" unless match("xyz");
reset;
print "ok 3 - match after reset succeeds\n" if match("xyz"); # should match again
print "ok 4 - reset + match before => match fails\n" unless match("xyz");

[toddr]

This worked before static PL_defstash but we don't really have a use case for fixing it.