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/fnearbyint.ll b/llvm/test/CodeGen/AMDGPU/fnearbyint.ll
index 4fa9ada..5423fad 100644
--- a/llvm/test/CodeGen/AMDGPU/fnearbyint.ll
+++ b/llvm/test/CodeGen/AMDGPU/fnearbyint.ll
@@ -1,6 +1,6 @@
-; RUN: llc -march=amdgcn -mcpu=SI -verify-machineinstrs < %s
+; RUN: llc -march=amdgcn -verify-machineinstrs < %s
 ; RUN: llc -march=amdgcn -mcpu=bonaire -verify-machineinstrs < %s
-; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s
+; RUN: llc -march=amdgcn -mcpu=tonga -mattr=-flat-for-global -verify-machineinstrs < %s
 
 ; This should have the exactly the same output as the test for rint,
 ; so no need to check anything.