This is on track to replace libupnp in the next version. Since libupnp
is not building with GCC10, do this now.

Also backported needed header patch.

Replace other patches with the upstream versions.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

Missing header for pid_t.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

This is a fairly massive update that adds new dependencies.

Switched the CMAKE_OPTIONS to use ON/OFF as is done elsewhere.

Added a patch fixing compilation with libiconv-stub/full.

Add a small debug option to write to syslog debug information.

Signed-off-by: Rosen Penev <rosenp@gmail.com>