Unreviewed, fix Windows build after r144910.

* JavaScriptCore.vcproj/JavaScriptCore/JavaScriptCore.vcproj:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144942 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Link the webkit_tests to XRENDER_LIBS.
This solves the linking failure when building against gtk2 like:
usr/lib/gcc/i586-suse-linux/4.7/../../../../i586-suse-linux/bin/ld:
Source/WebCore/platform/gtk/Programs_unittests_testcopyandpaste-GtkVersioning.o:
undefined reference to symbol 'XFree'
/usr/lib/gcc/i586-suse-linux/4.7/../../../../i586-suse-linux/bin/ld:
note: 'XFree' is defined in DSO /usr/lib/libX11.so.6 so try adding it
to the linker command line
/usr/lib/libX11.so.6: could not read symbols: Invalid operation

https://bugs.webkit.org/show_bug.cgi?id=111572

Patch by Dominique Leuenberger <dimstar@opensuse.org> on 2013-03-06
Reviewed by Gustavo Noronha Silva.

* GNUmakefile.am:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144943 268f45cc-cd09-0410-ab3c-d52691b4dbfc