[WebAssembly] Fix build failures introduced in r305769

[sbc100]

Summary

This fixes two build failures that only occur in certain
configurations:

• error: unused function 'operator<<'
• error: control reaches end of non-void function

lib/MC/WasmObjectWriter.cpp

Out << "Off=" << Offset << ", Sym=" << Symbol << ", Addend=" << Addend
         << ", Type=" << Type << ", FixupSection=" << FixupSection;
   }
 
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
 #endif
 };
 
-inline raw_ostream &operator<<(raw_ostream &OS,
-                               const WasmRelocationEntry &Rel) {
+raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) {
   Rel.print(OS);
   return OS;
 }
 
 class WasmObjectWriter : public MCObjectWriter {
   /// Helper struct for containing some precomputed information on symbols.
   struct WasmSymbolData {
     const MCSymbolWasm *Symbol;

lib/Object/WasmObjectFile.cpp

uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
     return 0;
   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
     return Exports[Sym.ElementIndex].Index;
   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
     return Sym.ElementIndex;
   }
+  llvm_unreachable("invalid symbol type");
 }
 
 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
   llvm_unreachable("not yet implemented");
   return 0;
 }
 
 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {