Enable FeatureFlatForGlobal on Volcanic Islands

This switches to the workaround that HSA defaults to
for the mesa path.

This should be applied to the 4.0 branch.

Patch by Vedran Miletić <vedran@miletic.net>

llvm-svn: 292982
diff --git a/llvm/test/CodeGen/AMDGPU/fp_to_uint.ll b/llvm/test/CodeGen/AMDGPU/fp_to_uint.ll
index d089c29..cbff9f2 100644
--- a/llvm/test/CodeGen/AMDGPU/fp_to_uint.ll
+++ b/llvm/test/CodeGen/AMDGPU/fp_to_uint.ll
@@ -1,5 +1,5 @@
 ; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck %s -check-prefixes=GCN,FUNC,SI
-; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck %s -check-prefixes=GCN,FUNC,VI
+; RUN: llc -march=amdgcn -mcpu=tonga -mattr=-flat-for-global -verify-machineinstrs < %s | FileCheck %s -check-prefixes=GCN,FUNC,VI
 ; RUN: llc -march=r600 -mcpu=redwood < %s | FileCheck %s -check-prefix=EG -check-prefix=FUNC
 
 declare float @llvm.fabs.f32(float) #1