[testsuite]: Add require fopenmp as needed

[Georg-Johann Lay]

There is a testcase that fails if no openmp is available.

This patch fixed that.

CCed contributor.

Johann


        * gcc.dg/cpp/pragma-3.c: Add dg-require-effective-target fopenmp.

Index: gcc.dg/cpp/pragma-3.c
===================================================================
--- gcc.dg/cpp/pragma-3.c	(revision 175811)
+++ gcc.dg/cpp/pragma-3.c	(working copy)
@@ -1,6 +1,7 @@
 /* 
    { dg-options "-fopenmp" }
    { dg-do preprocess }
+   { dg-require-effective-target fopenmp }
  */
 
 void foo (void)