[lit] Allow more file extensions for test cases.

This commit splits the file extensions before determining the test
format.  This allows libc++abi to add assembly-based test cases.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@283118 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed