Globally rename the header inclusion guard names.

Consistently apply this rule: the guard name is obtained from the
filename by stripping the leading "lib", converting '/' and '.'  to
'_' and uppercasing the resulting name. Guard names in the root
directory have to be prefixed by "FFMPEG_".

Originally committed as revision 15120 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/xiph.h

@@ -18,8 +18,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#ifndef FFMPEG_XIPH_H
-#define FFMPEG_XIPH_H
+#ifndef AVCODEC_XIPH_H
+#define AVCODEC_XIPH_H
 
 #include "libavutil/common.h"
 
@@ -40,4 +40,4 @@ int ff_split_xiph_headers(uint8_t *extradata, int extradata_size,
                           int first_header_size, uint8_t *header_start[3],
                           int header_len[3]);
 
-#endif /* FFMPEG_XIPH_H */
+#endif /* AVCODEC_XIPH_H */