Globally rename the header inclusion guard names.
Consistently apply this rule: the guard name is obtained from thefilename by stripping the leading "lib", converting '/' and '.' to'_' and uppercasing the resulting name. Guard names in the rootdirectory have to be prefixed by "FFMPEG_"....
Export data_to_hex() as private API in lavf, rename to ff_data_to_hex() andmove it from sdp.c into utils.c. Also add new header internal.h specificallyfor lavf-specific internal API. See discussion in "Realmedia patch" threadon mailinglist.
Originally committed as revision 15002 to svn://svn.ffmpeg.org/ffmpeg/trunk