Make LLVMToSPIRVBase comply with Rule of Five. (#2860)

LLVMToSPIRVBase had a custom destructor, but no copy constructor, no move constructor, no move assignment operator, and no copy assignment operator, so it was not complying with the Rule of Five. Explicitly add them as deleted to comply.

lib/SPIRV/SPIRVWriter.h

@@ -72,6 +72,10 @@ namespace SPIRV {
 class LLVMToSPIRVBase : protected BuiltinCallHelper {
 public:
   LLVMToSPIRVBase(SPIRVModule *SMod);
+  LLVMToSPIRVBase(const LLVMToSPIRVBase &Other) = delete;
+  LLVMToSPIRVBase &operator=(const LLVMToSPIRVBase &Other) = delete;
+  LLVMToSPIRVBase(LLVMToSPIRVBase &&Other) = delete;
+  LLVMToSPIRVBase &operator=(LLVMToSPIRVBase &&Other) = delete;
   bool runLLVMToSPIRV(Module &Mod);
 
   // This enum sets the mode used to translate the value which is