[Backport to llvm_release_210] Fix error propagation in parseSPIRV (KhronosGroup#3365)

Backport of PR KhronosGroup#3362 into `llvm_release_210`.

All commits applied cleanly.

Co-authored-by: Sven van Haastregt <sven.vanhaastregt@arm.com>

Author: github-actions[bot]

lib/SPIRV/libSPIRV/SPIRVModule.cpp

@@ -2576,7 +2576,7 @@ std::istream &SPIRVModuleImpl::parseSPIRV(std::istream &I) {
   SPIRVWord Header[5] = {0};
   I.read(reinterpret_cast<char *>(&Header), sizeof(Header));
 
-  SPIRVErrorLog ErrorLog = MI.getErrorLog();
+  SPIRVErrorLog &ErrorLog = MI.getErrorLog();
   if (!ErrorLog.checkError(!I.eof(), SPIRVEC_InvalidModule,
                            "input file is empty") ||
       !ErrorLog.checkError(!I.fail(), SPIRVEC_InvalidModule,