workaround git client bugs
Updated waf to 1.7.16
Removed git/submodule-workaround.

Enabling recursive submodule updates makes
submodule handling fine now.
mpv: Fixed build break since upstream switched to -std=c99

C99 defines __STRICT_ANSI__ and several macros like M_PI
won't get defined in MinGW's <math.h> header.

Undefine __STRICT_ANSI__ to bring it back.
Updated Android FFmpeg build script

Made it working outside of our build server.
Revised the compile time configrations.