Reorganization of *FLAGS

Using:
http://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#Warning-Options
http://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#Preprocessor-Options
http://gcc.gnu.org/onlinedocs/gcc/Link-Options.html#Link-Options
http://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html#ARM-Options