Add BUILD_RPI / BUILD_RPI_NO_X / BUILD_GLFW options
Default build option is BUILD_GLFW
When CMAKE_SYSTEM_NAME is given, determine build option by CMAKE_SYSTEM_NAME
(rpi : BUILD_RPI, rpi_noX : BUILD_RPI_NO_X, default : BUILD_GLFW)
fix BUILD_RPI, BUILD_RPI
* RPi firmware path prefix for cross compiling
* fix libraies ( add : math, X11 for with X )
* use c but cxx for glfw
change output path
add more examples
add shared build
Merge remote-tracking branch 'omniavinco/master'