Memory leak fix in LLVMToSPIRVBase::transExecutionMode (#2269)

Allocated SPIRVExecutionMode class wasn't added as dependant resource in
SPIRVModule. Fix some ASan errors in issue #2233.

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@1a19f6f

Author: bwlodarcz

llvm-spirv/lib/SPIRV/SPIRVWriter.cpp

@@ -5735,8 +5735,8 @@ bool LLVMToSPIRVBase::transExecutionMode() {
           break;
         unsigned NBarrierCnt = 0;
         N.get(NBarrierCnt);
-        BF->addExecutionMode(new SPIRVExecutionMode(
-            BF, static_cast<ExecutionMode>(EMode), NBarrierCnt));
+        BF->addExecutionMode(BM->add(new SPIRVExecutionMode(
+            BF, static_cast<ExecutionMode>(EMode), NBarrierCnt)));
         BM->addExtension(ExtensionID::SPV_INTEL_vector_compute);
         BM->addCapability(CapabilityVectorComputeINTEL);
       } break;