fourthTier: WebKit's build system should relink JavaScriptCore if LLVM's libraries changed but its headers didn't
https://bugs.webkit.org/show_bug.cgi?id=114926

Source/JavaScriptCore:

Reviewed by Geoffrey Garen.

Use a phony file that includes a phony header to force JavaScriptCore to be relinked
if necessary. The external LLVM-importing scripts will touch the header if the libraries
are known to have changed.

* JavaScriptCore.xcodeproj/project.pbxproj:
* ftl/WebKitLLVMLibraryAnchor.cpp: Added.

Tools:

Reviewed by Geoffrey Garen.

If the LLVM libraries change, then touch a phony header, which will force relink
of JavaScriptCore.

* Scripts/copy-webkitlibraries-to-product-directory:
(unpackIfNecessary):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@153126 268f45cc-cd09-0410-ab3c-d52691b4dbfc