[Clang] Make AMDGPU OpenCL tests require AMD registered target

Summary:
These tests likely always failed but was hidden by the expected return
value. Simply make them require AMDGPU as a registered target so they
don't fail on other machines.

Author: jhuber6

clang/test/SemaOpenCL/builtins-amdgcn-error-wave32.cl

@@ -4,6 +4,8 @@
 // RUN: %clang_cc1 -triple amdgcn-- -target-cpu gfx1010 -target-feature +wavefrontsize64 -verify -S -o - %s
 // RUN: %clang_cc1 -triple amdgcn-- -target-cpu gfx1010 -target-feature -wavefrontsize32 -verify -S -o - %s
 
+// REQUIRES: amdgpu-registered-target
+
 typedef unsigned int uint;
 
 void test_ballot_wave32(global uint* out, int a, int b) {

clang/test/SemaOpenCL/builtins-amdgcn-error-wave64.cl

@@ -2,6 +2,8 @@
 // RUN: %clang_cc1 -triple amdgcn-- -target-cpu gfx1010 -target-feature -wavefrontsize64 -verify -S -o - %s
 // RUN: %clang_cc1 -triple amdgcn-- -target-cpu gfx1010 -verify -S -o - %s
 
+// REQUIRES: amdgpu-registered-target
+
 // expected-no-diagnostics
 
 typedef unsigned long ulong;