Add explicit triples to AArch64 tests

Only Linux is supported at the moment, and other platforms quickly fault. As a
result these tests would fail on non-Linux hosts. It may be worth making the
tests more generic again as more platforms are supported.

llvm-svn: 174170
diff --git a/llvm/test/CodeGen/AArch64/flags-multiuse.ll b/llvm/test/CodeGen/AArch64/flags-multiuse.ll
index 80be052..940c146 100644
--- a/llvm/test/CodeGen/AArch64/flags-multiuse.ll
+++ b/llvm/test/CodeGen/AArch64/flags-multiuse.ll
@@ -1,4 +1,4 @@
-; RUN: llc -march=aarch64 -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=aarch64-none-linux-gnu -verify-machineinstrs < %s | FileCheck %s
 
 ; LLVM should be able to cope with multiple uses of the same flag-setting
 ; instruction at different points of a routine. Either by rematerializing the