Fix ld warning

[ianpartridge]

When building the TestFoundation target in Xcode 9 beta 4, ld reports the following warning:

Ld /Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Products/Debug/TestFoundation.app/Contents/MacOS/TestFoundation normal x86_64
    cd /Users/ipartrid/swift-corelibs-foundation
    export MACOSX_DEPLOYMENT_TARGET=10.11
    /Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch x86_64 -isysroot /Applications/Xcode-beta.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk -L/Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Products/Debug -F/Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Products/Debug -F../swift-corelibs-xctest/build/Debug -filelist /Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Intermediates.noindex/Foundation.build/Debug/TestFoundation.build/Objects-normal/x86_64/TestFoundation.LinkFileList -Xlinker -rpath -Xlinker @executable_path/../Frameworks -Xlinker -rpath -Xlinker @loader_path/../Frameworks -mmacosx-version-min=10.11 -Xlinker -object_path_lto -Xlinker /Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Intermediates.noindex/Foundation.build/Debug/TestFoundation.build/Objects-normal/x86_64/TestFoundation_lto.o -Xlinker -export_dynamic -Xlinker -no_deduplicate -fobjc-link-runtime -L/Applications/Xcode-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/macosx -Xlinker -add_ast_path -Xlinker /Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Intermediates.noindex/Foundation.build/Debug/TestFoundation.build/Objects-normal/x86_64/TestFoundation.swiftmodule -framework SwiftFoundation -Xlinker -dependency_info -Xlinker /Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Intermediates.noindex/Foundation.build/Debug/TestFoundation.build/Objects-normal/x86_64/TestFoundation_dependency_info.dat -o /Users/ipartrid/Library/Developer/Xcode/DerivedData/Foundation-dlbuoxyagtlausbjtyopapynebeb/Build/Products/Debug/TestFoundation.app/Contents/MacOS/TestFoundation

ld: warning: directory not found for option '-F../swift-corelibs-xctest/build/Debug'

As far as I can tell, this directory is just not used by the build system and I'm not sure why it's been added to the Framework Search Paths for that target.

This PR removes the references, and hence the warning. Also minor whitespace fixes which Xcode did at the same time as removing the references.

[alblue]

Do you have swift-corelibs-xctest checked out and built in the relative path indicated? This is only a warning if such a directory doesn't exist. Having said that, it does look like that it's missing a . before the build.

I'm not sure if there are other reasons why it's there; perhaps it is an historical artefact of the way the project was set up in the first place? Or something to do with how it can be built from the command line with swift pm?

[ianpartridge]

Yes, swift-corelibs-xctest is in the correct location (the build wouldn't run at all if it wasn't). build/ is an SPM thing, yes, but an SPM build can't be driven from Xcode yet, so this made no sense to me.

Hopefully @parkera or @phausler know what's going on and whether it's safe to just remove the references (so far, I can't see any problems with doing so).

[ianpartridge]

Hmm looks like this was added in #1038 - @spevans?

[spevans]

I think this may be something leftover from Xcode8 as I have just tried your change with Xcode9 and the tests still build and run ok. Im sure there used to be a build directory but I don't see it anymore so Im fine with this change.

[ianpartridge]

@swift-ci please test