Move ENABLE macros for WebCore out from Platform.h
https://bugs.webkit.org/show_bug.cgi?id=105735

Unreviewed, build fix when NETSCAPE_PLUGIN_API is disabled.

Enable ENABLE_PLUGIN_PACKAGE_SIMPLE_HASH even if
NETSCAPE_PLUGIN_API is disabled (Qt, Efl, GTK, WX ports).

Patch by Laszlo Gombos <l.gombos@samsung.com> on 2013-02-18

* wtf/FeatureDefines.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143248 268f45cc-cd09-0410-ab3c-d52691b4dbfc