[PATCH testsuite]Fix pr83126.c failure for bare-metal toolchains

[Bin Cheng]

Hi,
The new test pr83126.c requires pthread for compiling, this simple patch skips 
it
for bare-metal toolchains.

Test checked.  Is it OK?

Thanks,
bin

gcc/testsuite
2018-03-22  Bin Cheng  <bin.ch...@arm.com>

        * gcc.dg/graphite/pr83126.c: Require pthread for the test.
diff --git a/gcc/testsuite/gcc.dg/graphite/pr83126.c 
b/gcc/testsuite/gcc.dg/graphite/pr83126.c
index 663d059..36bf5d5 100644
--- a/gcc/testsuite/gcc.dg/graphite/pr83126.c
+++ b/gcc/testsuite/gcc.dg/graphite/pr83126.c
@@ -1,3 +1,4 @@
+/* { dg-do compile { target pthread } }  */
 /* { dg-additional-options "-w -ftree-parallelize-loops=2 
-floop-parallelize-all -O1" }  */
 
 void