For Wardje both tests (with and without Xxf86vm) failed because of gcc
being unable to execute 'as'. His error log showed also tests executed
by FindX11 (provided by CMake itself) failed because of this.
Not sure what is broken exactly but this patch circumvents it.
git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@10980 178a84e3-b1eb-0310-8ba1-8eac791a3b58