[FFmpeg-devel] [PATCH] configure: autodetect libglslang ldflags

[Matthew White]

> Also, how does this work when cross compiling - won't the "glslang" binary 
> be for the foreign cross target? Or is it something like the sdl-config 
> script which is a local shell script that can give relevant build flags (a 
> design preceding pkg-config)?

I don't have an answer to that, in FFmpeg's configure I saw using something like
`[ -x "$(command -v gzip)" ] && enable gzip`, so I replicated it to check on the
glslang's binary.  I guess that who is ready to cross compile may try this patch
with glslang installed to tell what's happening.

I worked on this fix in GNU/Linux Gentoo.  Trying both glslang 14.0.0 and 13.1.1
only the latter requires "-lOSDependent -lHLSL -lOGLCompiler".  I configured the
compilation with `./configure --enable-libglslang`, the stub flags/libraries are
not required for glslang 14.0.0.  I can compile FFmpeg 6.1.1 by backporting this
patch.

This patch may be dropped altogether by locking FFmpeg on glslang 14.0.0 and up,
and removing the stub "-lOSDependent -lHLSL -lOGLCompiler" flags/libraries.