Clean up calls to WriteBitcodeToFile (NFC)

Remove a default parameter value being passed unnecessarily, which
also reduces the changes required when this parameter is changed in
D18763.

Document the remaining non-default bool value passed for another
parameter.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265348 91177308-0d34-0410-b5e6-96231b3b80d8

lib/LTO/ThinLTOCodeGenerator.cpp

@@ -91,7 +91,7 @@ static void saveTempBitcode(const Module &TheModule, StringRef TempDir,
   if (EC)
     report_fatal_error(Twine("Failed to open ") + SaveTempPath +
                        " to save optimized bitcode\n");
-  WriteBitcodeToFile(&TheModule, OS, true, false);
+  WriteBitcodeToFile(&TheModule, OS, /* ShouldPreserveUseListOrder */ true);
 }
 
 bool IsFirstDefinitionForLinker(const GlobalValueInfoList &GVInfo,

tools/llvm-lto/llvm-lto.cpp

@@ -316,7 +316,7 @@ static void writeModuleToFile(Module &TheModule, StringRef Filename) {
   std::error_code EC;
   raw_fd_ostream OS(Filename, EC, sys::fs::OpenFlags::F_None);
   error(EC, "error opening the file '" + Filename + "'");
-  WriteBitcodeToFile(&TheModule, OS, true, false);
+  WriteBitcodeToFile(&TheModule, OS, /* ShouldPreserveUseListOrder */ true);
 }
 
 class ThinLTOProcessing {