[PATCH] x86-64/PE: adjust PR ld/26659 testcase for Cygwin

[Nick Clifton]

Hi Jan,

> ld/
> 2021-04-XX  Jan Beulich  <jbeulich@suse.com>
> 
> 	PR ld/26659
> 	* testsuite/ld-pe/pr26659-weak-undef-sym.d: Relax for Cygwin.

Approved - please apply.

Cheers
   Nick