add -gdwarf-2 compiler flag to help debugger to see local variable

thanks to the article:
http://stackoverflow.com/questions/12595631/debugging-with-gdb-on-a-program-with-no-optimization-but-still-there-is-no-symbo

Signed-off-by: Wayne Wolf <wayne.ron.wu@googlemail>
two basic built-in shader implemented.

Signed-off-by: Wayne Wolf <wayne.ron.wu@googlemail>