If SDL_SaveBMP_RW() was called with NULL passed as SDL_RWops argument, different
values were returned depending on SDL_GetError(). If no error was set before the
call (or SDL_ClearError() was called) then 0 was returned. This is wrong because
nothing was saved. If an error was set before the call then -1 was returned.
This was fixed by directly returning -1 for NULL input instead of deciding based
on SDL_GetError(). No new error is set because this would otherwise override a
maybe more useful error set in SDL_RWFromFile() which is used by SDL_SaveBMP().
Jonas Kulla
The configure script didn't differentiate between Linux and Android, unconditionally compiling in the unix implementation of SDL_sysfilesystem.c.
I'm probably one of the very few people building SDL for android using classic configure + standalone toolchain, so this has gone undetected all along.
