[iOS] Get rid of iOS.xcconfig

[iOS] Get rid of iOS.xcconfig
https://bugs.webkit.org/show_bug.cgi?id=135809

Reviewed by Joseph Pecoraro.

All iOS.xcconfig did was include AspenFamily.xcconfig, so there's no need for the indirection.

Source/bmalloc:

* Configurations/Base.xcconfig:
* Configurations/iOS.xcconfig: Removed.
* bmalloc.xcodeproj/project.pbxproj:

Source/JavaScriptCore:

* Configurations/Base.xcconfig:
* Configurations/iOS.xcconfig: Removed.
* JavaScriptCore.xcodeproj/project.pbxproj:

Source/ThirdParty:

* gtest/xcode/Config/General.xcconfig:
* gtest/xcode/Config/iOS.xcconfig: Removed.
* gtest/xcode/gtest.xcodeproj/project.pbxproj:

Source/ThirdParty/ANGLE:

* ANGLE.xcodeproj/project.pbxproj:
* Configurations/Base.xcconfig:
* Configurations/iOS.xcconfig: Removed.

Source/WebCore:

* Configurations/Base.xcconfig:
* Configurations/iOS.xcconfig: Removed.
* WebCore.xcodeproj/project.pbxproj:

Source/WebKit:

* WebKit.xcodeproj/project.pbxproj:

Source/WebKit/mac:

* Configurations/Base.xcconfig:
* Configurations/iOS.xcconfig: Removed.

Source/WebKit2:

* Configurations/Base.xcconfig:
* Configurations/iOS.xcconfig: Removed.
* WebKit2.xcodeproj/project.pbxproj:

Source/WTF:

* Configurations/Base.xcconfig:
* Configurations/iOS.xcconfig: Removed.
* WTF.xcodeproj/project.pbxproj:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@172482 268f45cc-cd09-0410-ab3c-d52691b4dbfc