Fix gold-plugin Windows build

r365588 missed one instance of integer file descriptor use in
gold-plugin.cpp.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366786 91177308-0d34-0410-b5e6-96231b3b80d8

tools/gold/gold-plugin.cpp

@@ -513,8 +513,8 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
       offset = file->offset;
     }
     ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
-        MemoryBuffer::getOpenFileSlice(file->fd, file->name, file->filesize,
-                                       offset);
+        MemoryBuffer::getOpenFileSlice(sys::fs::convertFDToNativeFile(file->fd),
+                                       file->name, file->filesize, offset);
     if (std::error_code EC = BufferOrErr.getError()) {
       message(LDPL_ERROR, EC.message().c_str());
       return LDPS_ERR;