[OMPIRBuilder] Fix use of uninitialized variable.

The code in OpenMPIRBuilder::getTargetEntryUniqueInfo calls
ID.getDevice() even when getUniqueID has failed and ID is
un-initialized. This caused a sanitizer fail for me in
#145026. Fix it by giving
a default value to ID. The value chosen is the same as used in
OpenMPToLLVMIRTranslation.cpp.

Author: abidh

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

@@ -9846,7 +9846,7 @@ void OffloadEntriesInfoManager::getTargetRegionEntryFnName(
 TargetRegionEntryInfo
 OpenMPIRBuilder::getTargetEntryUniqueInfo(FileIdentifierInfoCallbackTy CallBack,
                                           StringRef ParentName) {
-  sys::fs::UniqueID ID;
+  sys::fs::UniqueID ID(0xdeadf17e, 0);
   auto FileIDInfo = CallBack();
   uint64_t FileID = 0;
   std::error_code EC = sys::fs::getUniqueID(std::get<0>(FileIDInfo), ID);