debug/92763 Fix testcase to require fopenmp

The testcase fails to link on targets without -pthread which is
implied by -fopenmp. Use dg-require-effective-target fopenmp to avoid
this problem.

2020-01-24  Christophe Lyon  <christophe.lyon@linaro.org>

	PR debug/92763
	* g++.dg/debug/pr92763.C: Require fopenmp.

gcc/testsuite/ChangeLog

+2020-01-24  Christophe Lyon  <christophe.lyon@linaro.org>
+
+	PR debug/92763
+	* g++.dg/debug/pr92763.C: Require fopenmp.
+
 2020-01-23  David Malcolm  <dmalcolm@redhat.com>
 
 	PR analyzer/93367

gcc/testsuite/g++.dg/debug/pr92763.C

 // { dg-do compile }
+// { dg-require-effective-target fopenmp }
 // { dg-additional-options "-fno-var-tracking-assignments -fopenmp" }
 
 struct A