Revert "Disable swiftcall test on windows: More brutal way to appease windows bots"
Revert "Disable swiftcall test on windows: More brutal way to appease windows bots"

This reverts commit r284174. The tests pass for me locally. It must have
been a 2015 only crash.

Fixes PR30699

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@284781 91177308-0d34-0410-b5e6-96231b3b80d8

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