Revert "Introducing the Platform Abstraction Layer (PAL)"

Revert "Introducing the Platform Abstraction Layer (PAL)"
https://bugs.webkit.org/show_bug.cgi?id=144751

Unreviewed.

PAL should be a new target inside WebCore, rather than a top-level folder.

.:

* WebKit.xcworkspace/contents.xcworkspacedata: Add it to the workspace.

Source/JavaScriptCore:

* Configurations/FeatureDefines.xcconfig: Updated

Source/WebCore:

* WebCore.xcodeproj/project.pbxproj:
* Configurations/FeatureDefines.xcconfig:

Source/WebKit/mac:

* Configurations/FeatureDefines.xcconfig: Updated

Source/WebKit2:

* Configurations/FeatureDefines.xcconfig: Updated

Tools:

* Scripts/build-webkit: Add it to build-webkit.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@183940 268f45cc-cd09-0410-ab3c-d52691b4dbfc