Include the nettle/hogweed crypto libraries in the pkg-config file

These libraries are linked and used as directly as we use gnutls
itself. This fixes linking for callers if librtmp is built
statically or if the linker doesn't support transitive linking.
Include -lgmp in the pkg-config file when building with gnutls

This is required when a user of librtmp is linking statically to
librtmp (when it is built with gnutls support).

Ideally everything of the Requires line should be in
Requires.private, and -lgmp would go into Libs.private - but if
only building a static lib, they should go where they are right
now instead. Keeping all of this where it is right now, for now,
for simplicity.
Merge branch 'master' into ksv
Bump the SO_VERSION to 1

Commit a9282329c3 changed the layout of the RTMP struct, making
it ABI-incompatible with previous versions.
Correct the count of bytes written to the initial FLV buffer

This matters if the buffer overflows, when the count is used
for patching the buffer back together. This happens if there
are multiple video packets with zero timestamp at the start
of the stream (before any audio packets), enough to fill the buffer.
Free the extra read buffer if the initial FLV buffer overflowed

This fixes a leak in this cornercase.
Fix leaks in AMF objects that contain arrays
Merge branch 'master' of git://git.ffmpeg.org/rtmpdump into ksv

Conflicts:
	librtmp/rtmp.c