[llvm-rc] Don't strictly require quotes around external file names

[llvm-rc] Don't strictly require quotes around external file names

Regardless of what docs may say, existing resource files in the
wild can use this syntax.

Rename a file used in an existing test, to make it usable for unquoted
paths.

Differential Revision: https://reviews.llvm.org/D46511

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331747 91177308-0d34-0410-b5e6-96231b3b80d8