MDM9x15 build environment (L4 running on Apps processor)

For 9x15, there are 3 separate images, modem/app/boot, the build environments are shown below:

APSS	apps_proc\build\ms		RVCT 41P514	Python 2.5.2
MPSS	modem_proc\build\ms		Hexagon 3.0.05	Python 2.5.2
Boot Images	boot_images\core\bsp\build		RVCT 41P514	Python 2.5.2