JIT64: correctly sign-extend immediate RC values
Fix more warnings from #579
Merge pull request #609 from Tilka/fix_warnings

Fix more warnings from #579
VideoBackendBase: Remove unused stub Initialize implementation

Both D3D and OGL have their own overrides, so this isn't used.
X11Utils: Don't depend on wx

We want to have two build targets: Main and MainNoGUI, and this code
will be linked against in both cases, so the ifdef isn't enough for
this case.

Just append to a vector of strings, and then convert it after the fact.
DolphinWX: Allow building both GUI and NoGUI at the same time

Restructure our build system so we have multiple targets. Right now we
only build MainNoGUI if we are using X11, since that's the only truly
supported backend: the OS X code actually doesn't compile, according to
comments made on IRC.
CMakeLists: Try to fix the X11 detection on OS X
Merge pull request #751 from FioraAeterna/fixsignext

JIT64: correctly sign-extend immediate RC values
Merge pull request #755 from magcius/clean-up-nogui

Allow building MainNoGUI and MainGUI simultaneously
Merge pull request #756 from magcius/remove-unused

VideoBackendBase: Remove unused stub Initialize implementation