[PGO][Offload] Fix missing names bug in GPU PGO (#166444)

After #163011 was merged, the tests in
[`offload/test/offloading/gpupgo`](https://github.com/llvm/llvm-project/compare/main...EthanLuisMcDonough:llvm-project:gpupgo-names-fix-pr?expand=1#diff-f769f6cebd25fa527bd1c1150cc64eb585c41cb8a8b325c2bc80c690e47506a1)
broke because the offload plugins were no longer able to find
`__llvm_prf_nm`. This pull request explicitly makes `__llvm_prf_nm`
visible to the host on GPU targets and reverses the changes made in
f7e9968a5b.

llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp

@@ -1944,6 +1944,10 @@ void InstrLowerer::emitNameData() {
   NamesVar = new GlobalVariable(M, NamesVal->getType(), true,
                                 GlobalValue::PrivateLinkage, NamesVal,
                                 getInstrProfNamesVarName());
+  if (isGPUProfTarget(M)) {
+    NamesVar->setLinkage(GlobalValue::ExternalLinkage);
+    NamesVar->setVisibility(GlobalValue::ProtectedVisibility);
+  }
 
   NamesSize = CompressedNameStr.size();
   setGlobalVariableLargeSection(TT, *NamesVar);

offload/test/offloading/gpupgo/pgo_atomic_teams.c

@@ -18,7 +18,6 @@
 
 // REQUIRES: amdgpu
 // REQUIRES: pgo
-// XFAIL: amdgpu
 
 int test1(int a) { return a / 2; }
 int test2(int a) { return a * 2; }

offload/test/offloading/gpupgo/pgo_atomic_threads.c

@@ -18,7 +18,6 @@
 
 // REQUIRES: amdgpu
 // REQUIRES: pgo
-// XFAIL: amdgpu
 
 int test1(int a) { return a / 2; }
 

offload/test/offloading/gpupgo/pgo_device_and_host.c

@@ -50,7 +50,6 @@
 
 // REQUIRES: amdgpu
 // REQUIRES: pgo
-// XFAIL: amdgpu
 
 int main() {
   int host_var = 0;

offload/test/offloading/gpupgo/pgo_device_only.c

@@ -16,7 +16,6 @@
 
 // REQUIRES: amdgpu
 // REQUIRES: pgo
-// XFAIL: amdgpu
 
 int test1(int a) { return a / 2; }
 int test2(int a) { return a * 2; }