Move UNUSED_PARAM and UNUSED_LABEL macros to Compiler.h
https://bugs.webkit.org/show_bug.cgi?id=115997

Reviewed by Benjamin Poulain.

UnusedParam.h predates Compiler.h and the macros defined there should just go into Compiler.h

* wtf/Compiler.h:
(unusedParam):
* wtf/UnusedParam.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149978 268f45cc-cd09-0410-ab3c-d52691b4dbfc