Add a check to see if -Wno-unused-result is supported by the compiler.
Fix some compiler warnings in the wiiuse code.
Fix a bug in the wxGTK panic alert code.
git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6399 8ced0084-cf51-0410-be5f-012b33b47a6e