Regression since 6dfcbd80

Tested-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: James Almer <jamrial@gmail.com>

Remove the SDL_main define from the global cflags but not from the
ffplay cflags, and the -mwindows linker option from extralibs instead
of overriding it with the addition of -mconsole.

Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

Signed-off-by: James Almer <jamrial@gmail.com>

(Cherry-picked from libav commit 3c0efbd0)

Signed-off-by: James Almer <jamrial@gmail.com>

None of them are specific to the YASM assembler.

(Cherry-picked from libav commit 39e208f4)

Signed-off-by: James Almer <jamrial@gmail.com>

It's not used by anything, has dubious usefulness, the reasons for which
it was introduced are no longer valid, and only serves to add complexity
to the build system.

Signed-off-by: James Almer <jamrial@gmail.com>

Original work by Yogender Gupta <ygupta@nvidia.com>

Regression since 6fdd35a3