On some platforms (such as msys), symlinks are (poorly) emulated
by simply creating a copy of the file.

This means that when building out of tree, the build tree gets
a copy of the original makefile, which can lead to unintuitive
build errors when the original makefile gets updated later.

Instead simply create a stub makefile which includes the real
one.

Signed-off-by: Martin Storsjö <martin@martin.st>

Signed-off-by: Diego Biurrun <diego@biurrun.de>

Signed-off-by: Diego Biurrun <diego@biurrun.de>

data[0] may be NULL for valid frames with hwaccel pixel formats.

This makes RTMPT work again - it was broken by 5d876be8.

Signed-off-by: Martin Storsjö <martin@martin.st>