PowerPC: add Linux triple to TLS tests

The tests were failing on OS X.

llvm-svn: 197146
diff --git a/llvm/test/CodeGen/PowerPC/tls.ll b/llvm/test/CodeGen/PowerPC/tls.ll
index 2274edf..fd4c682 100644
--- a/llvm/test/CodeGen/PowerPC/tls.ll
+++ b/llvm/test/CodeGen/PowerPC/tls.ll
@@ -1,6 +1,8 @@
 ; RUN: llc -O0 < %s -march=ppc64 -mcpu=ppc64 | FileCheck -check-prefix=OPT0 %s
 ; RUN: llc -O1 < %s -march=ppc64 -mcpu=ppc64 | FileCheck -check-prefix=OPT1 %s
 
+target triple = "powerpc64-unknown-linux-gnu"
+
 @a = thread_local global i32 0, align 4
 
 ;OPT0-LABEL:          localexec: