[OpenMP][FIX] Remove AssertingVHs that outlive their values

The map with AssertingVHs has been moved into the OpenMPIRBuilder which extended their lifetime.
On NVIDIA this will cause an assertion. This simply removes the AssertingVH wrapper.

clang/test/OpenMP/target_codegen_ref_assertion_vh.cpp

@@ -0,0 +1,11 @@
+// REQUIRES: nvptx-registered-target
+//
+// Test target codegen - host bc file has to be created first.
+// RUN: %clang_cc1 -verify -fopenmp -x c++ -triple powerpc64le-unknown-unknown -fopenmp-targets=nvptx64-nvidia-cuda -emit-llvm-bc %s -o %t-ppc-host.bc
+// RUN: %clang_cc1 -verify -fopenmp -x c++ -triple nvptx64-unknown-unknown -fopenmp-targets=nvptx64-nvidia-cuda %s -fopenmp-is-device -fopenmp-host-ir-file-path %t-ppc-host.bc -o %t.final
+// expected-no-diagnostics
+
+#pragma omp begin declare target
+constexpr int A[] = {1,2,3,4,5};
+int f(int i) { return A[i]; }
+#pragma omp end declare target

llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h

@@ -1077,7 +1077,7 @@ class OpenMPIRBuilder {
   /// <critical_section_name> + ".var" for "omp critical" directives; 2)
   /// <mangled_name_for_global_var> + ".cache." for cache for threadprivate
   /// variables.
-  StringMap<AssertingVH<Constant>, BumpPtrAllocator> InternalVars;
+  StringMap<Constant*, BumpPtrAllocator> InternalVars;
 
   /// Create the global variable holding the offload mappings information.
   GlobalVariable *createOffloadMaptypes(SmallVectorImpl<uint64_t> &Mappings,