Simplify Xcode configuration settings that used to vary between OS versions.

Simplify Xcode configuration settings that used to vary between OS versions.

Reviewed by Dan Bernstein.

Source/JavaScriptCore:

* Configurations/Base.xcconfig:
* Configurations/DebugRelease.xcconfig:
* Configurations/JavaScriptCore.xcconfig:

Source/ThirdParty:

* gtest/xcode/Config/General.xcconfig:

Source/ThirdParty/ANGLE:

* Configurations/Base.xcconfig:
* Configurations/DebugRelease.xcconfig:

Source/WebCore:

* Configurations/Base.xcconfig:
* Configurations/DebugRelease.xcconfig:
* Configurations/WebCore.xcconfig:

Source/WebKit/mac:

* Configurations/Base.xcconfig:
* Configurations/DebugRelease.xcconfig:
* Configurations/WebKit.xcconfig:

Source/WebKit2:

* Configurations/Base.xcconfig:
* Configurations/WebKit2.xcconfig:

Source/WTF:

* Configurations/Base.xcconfig:
* Configurations/DebugRelease.xcconfig:

Tools:

* DumpRenderTree/mac/Configurations/Base.xcconfig:
* DumpRenderTree/mac/Configurations/DebugRelease.xcconfig:
* MiniBrowser/Configurations/Base.xcconfig:
* MiniBrowser/Configurations/DebugRelease.xcconfig:
* TestWebKitAPI/Configurations/Base.xcconfig:
* TestWebKitAPI/Configurations/DebugRelease.xcconfig:
* WebKitTestRunner/Configurations/Base.xcconfig:
* WebKitTestRunner/Configurations/DebugRelease.xcconfig:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@132860 268f45cc-cd09-0410-ab3c-d52691b4dbfc