Changes to allow the font subsystem to be built without enabling the entire graphics system (CONFIG_NX).  Adds CONFIG_NXFONTS and CONFIG_NXGLIB.  NX and NXFONTS are still pretty heavily entangled

Squashed commit of the following:

    libnx: Need to duplicate some Kconfig setting for NXFONTs if it can be configured and built independently of NX.  Also includes some build-related fixes.

    configs/sim:  Disable NX graphics support in the fb configuration.

    libnx:  Basic configuration and build changes to support building font support independend of the NX server.