[llvm] [runtimes] Fix parsing of LIB{CXX,CXXABI,UNWIND}_TEST_PARAMS (PR #67691)

[Vladimir Vereschaka via llvm-commits]

vvereschaka wrote:

@arichardson ,
would you commit these changes without @ldionne 's approval? or revert your #66545?

https://github.com/llvm/llvm-project/pull/67691