build: Separate building programs linking against libav* from building av*

This will allow cleaner integration of building example programs.
build: Integrate multilibrary examples into the build system

This includes moving libavformat/output-example to doc/examples/output.
aacsbr: Add some const casts to silence warnings in ff_sbr_apply()
vc1: Reset numref if fieldmode is not set

There are samples in the wild with B-frames and P-frames with different
interlace mode.

CC: libav-stable@libav.org
Reported-by: Jean-Baptiste Kempf <jb@videolan.org>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
metasound: add last missing modes (8kHz @ 6kbps per channel)

Signed-off-by: Anton Khirnov <anton@khirnov.net>
MSN Audio support

This is essentially a MS GSM decoder extension that supports more
sampling rates and lower bitrates.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
mpeg12dec: Extract CC user data into frame side data

Signed-off-by: Anton Khirnov <anton@khirnov.net>
lavc: remove mp3_header_(de)compress bitstream filters

They mangle the mp3 header in a non-standard way to save a few bytes.
People who care about space so much should just use a more efficient
codec.
Makefile: Fix building programs on systems with a nonempty executable suffix

This fixes leftover issues from 14abeaa4 which caused make
rules for programs to not match up properly when the executable
suffix was nonempty.

Signed-off-by: Martin Storsjö <martin@martin.st>
configure: Restore doc option to disable building the documentation

Also add appropriate dependency declarations for perl and texi2html.
build: Check for pod2man instead of perl for manual page generation

Some systems provide Perl without pod2man.