Memory leaks fix in SPIRVFunction::decodeBB (#2268)

SPIRVEntry is created by function getEntry() but not deleted in a few
frame ending branches.

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@59f15de

Author: bwlodarcz

llvm-spirv/lib/SPIRV/libSPIRV/SPIRVFunction.cpp

@@ -153,6 +153,7 @@ bool SPIRVFunction::decodeBB(SPIRVDecoder &Decoder) {
                                           std::to_string(Entry->getOpCode()))) {
       // Bail out if the opcode is not implemented.
       Module->setInvalid();
+      delete Entry;
       return false;
     }
 
@@ -164,6 +165,7 @@ bool SPIRVFunction::decodeBB(SPIRVDecoder &Decoder) {
                                SPIRVDebug::DebugNoLine) ||
                Inst->isExtInst(SPIRVEIS_NonSemantic_Shader_DebugInfo_200,
                                SPIRVDebug::DebugNoLine)) {
+      delete Entry;
       continue;
     } else if (Inst->isExtInst(SPIRVEIS_NonSemantic_Shader_DebugInfo_100,
                                SPIRVDebug::DebugLine) ||