global. coredump

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=3441

Reported by Johan H Sundström, IDA jhs@pike.ida.liu.se

This code produces a coredumpwith pike 7.4 at pelix:

int a;
int main()
{
  int b;
  b += global.a;
}

Substituting "+=" for "=" instead renders the error:

core.pike:5:Assigning a void expression.
Pike: Failed to compile script:
Compilation failed.