utils/llvm-lit: Generate "llvm-lit.py" rather than "llvm-lit" on Win32 hosts to let llvm-lit.py --use-processes work.

llvm-lit needs suffix.py for multiprocess to find a main module.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196328 91177308-0d34-0410-b5e6-96231b3b80d8
check-llvm: Ask llvm-config about assertion mode, instead of llc.

Add --assertion-mode to llvm-config. It emits ON or OFF according to NDEBUG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196329 91177308-0d34-0410-b5e6-96231b3b80d8