Fix Xcode ansi.c/h, AppKit.framework, and USE_HEADERMAP issues.

[AliceLR]

Fixes the following issues with the Xcode project (most are my fault or due to things I added ;-():

• ansi.{c,h} were missing from the editor target.
• AppKit.framework was missing from the editor target (required to correctly link clipboard_cocoa.m).
• USE_HEADERMAP was causing system headers to pull in MZX headers in place of some system headers, causing numerous compilation issues in clipboard_cocoa.m related to bool (which compat.h undefines).
• Added libxmp/src and libxmp/src/loaders to the user header include paths for the core target to fix libxmp compilation after the above change.
• Disabled C++ exceptions and RTTI for all targets.

TODO:

• event_sdl.c still doesn't link due to, for some reason, it being unable to find SDL_GameControllerAddMappingsFromRW. old SDL2 framework in the path :(