doc: move syntax and eval chapters from libavutil to ffmpeg-utils

Move utilities description to a dedicated manual, consistent with what I
did with the rest of the documentation.

doc/Makefile

@@ -6,7 +6,7 @@ DOCLIBS-$(CONFIG_AVFORMAT) += libavformat
 DOCLIBS-$(CONFIG_AVDEVICE) += libavdevice
 DOCLIBS-$(CONFIG_AVFILTER) += libavfilter
 
-COMPONENTS=$(PROGS-yes) ffmpeg-codecs ffmpeg-devices ffmpeg-filters ffmpeg-resampler ffmpeg-scaler ffmpeg-formats
+COMPONENTS=$(PROGS-yes) ffmpeg-codecs ffmpeg-devices ffmpeg-filters ffmpeg-resampler ffmpeg-scaler ffmpeg-formats ffmpeg-utils
 
 MANPAGES    = $(COMPONENTS:%=doc/%.1)    $(DOCLIBS-yes:%=doc/%.3)
 PODPAGES    = $(COMPONENTS:%=doc/%.pod)  $(DOCLIBS-yes:%=doc/%.pod)

doc/ffmpeg-utils.texi

@@ -0,0 +1,38 @@
+\input texinfo @c -*- texinfo -*-
+
+@settitle FFmpeg Utilities Documentation
+@titlepage
+@center @titlefont{FFmpeg Utilities Documentation}
+@end titlepage
+
+@top
+
+@contents
+
+@chapter Description
+@c man begin DESCRIPTION
+
+This document describes some generic features and utilities provided
+by the libavutil library.
+
+@c man end DESCRIPTION
+
+@include syntax.texi
+@include eval.texi
+
+@ignore
+
+@setfilename ffmpeg-utils
+@settitle FFmpeg utilities
+
+@c man begin SEEALSO
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavutil(3)
+@c man end
+
+@c man begin AUTHORS
+See Git history (git://source.ffmpeg.org/ffmpeg)
+@c man end
+
+@end ignore
+
+@bye

doc/libavutil.texi

@@ -20,16 +20,13 @@ enumerations for pixel and sample formats).
 
 @c man end DESCRIPTION
 
-@include syntax.texi
-@include eval.texi
-
 @ignore
 
 @setfilename libavutil
 @settitle multimedia-biased utility library
 
 @c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1)
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), ffmpeg-utils(1)
 @c man end
 
 @c man begin AUTHORS