Move some commands from ./CMakeLists.txt to Source/cmake

Move some commands from ./CMakeLists.txt to Source/cmake
https://bugs.webkit.org/show_bug.cgi?id=148003

Patch by Alex Christensen <achristensen@webkit.org> on 2015-08-13
Reviewed by Brent Fulgham.

* CMakeLists.txt:
.:

Moved functionality to WebKitCommon.cmake and WebKitFS.cmake and made conditional
so we can change directory structure from command line parameters.
* Source/cmake/WebKitCommon.cmake: Added.
* Source/cmake/WebKitFS.cmake:

Source/JavaScriptCore:

Added commands needed to build JSC by itself.

Source/WebCore:

Added commands needed to build WebCore by itself.

Source/WebKit:

Added some commands needed to build WebKit by itself.

Source/WTF:

Added commands needed to build WTF by itself.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@188428 268f45cc-cd09-0410-ab3c-d52691b4dbfc