Misc: add a test for TargetParser usage
Misc: add a test for TargetParser usage

Ensure that an invalid value passed to target parser does not cause an assertion
in +Asserts builds.

Supporting test for PR26839.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@262780 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang