Fix the production build.

Fix the production build.

Don't rely on USE_INTERNAL_SDK being set for the Production configuration since UseInternalSDK.xcconfig won't
be at the expected relative path when working from installed source.

Source/JavaScriptCore:

* Configurations/Base.xcconfig:

Source/ThirdParty/ANGLE:

* Configurations/Base.xcconfig:

Source/WebCore:

* Configurations/Base.xcconfig:

Source/WebKit/mac:

* Configurations/Base.xcconfig:

Source/WebKit2:

* Configurations/Base.xcconfig:

Source/WTF:

* Configurations/Base.xcconfig:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@165677 268f45cc-cd09-0410-ab3c-d52691b4dbfc