[lit] Use the build.py script in the case-insensitive test
[lit] Use the build.py script in the case-insensitive test

This makes the test build correctly regardless of whether we use VS or ninja to run the tests

git-svn-id: 4c4cc70b1ef44ba2b7963015e681894188cea27e@348544 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb