Use libswscale for YUV->RGBA conversion if libvideogfx is not available.
Update CXXFLAGS/LDFLAGS depending on available libraries.
Install packages required to build sherlock265 example.
Initialize context and image to NULL.
Use "AC_MSG_NOTICE" instead of "echo".
This will honor options "--quiet" or "--silent".
Merge pull request #53 from fancycode/sherlock_swscale

Use libswscale for YUV->RGBA conversion if libvideogfx is not available.