lib: play/add_intf/exit_handler cleanup

Supersedes !4852 (closed)

Doing a new MR as this is a major change.

cf. discussion here !4852 (comment 424558)

WARNING: This MR remove the ability to spawn a specific interface from LibVLC

(it is ok for me, but is it for everyone?)

bin/Makefile.am

@@ -26,7 +26,7 @@ endif
 #
 # Main VLC executable
 #
-vlc_LDADD = ../lib/libvlc.la
+vlc_LDADD = ../lib/libvlc.la ../src/libvlccore.la
 vlc_CPPFLAGS = $(AM_CPPFLAGS)
 if !HAVE_WIN32
 vlc_SOURCES = vlc.c override.c