Bump libvlccore version to compensate 1.0-bugfix age increase

I don't know if this is really useful. On Linux it is not really useful
given the libtool versioning algorithm (VER:REV:AGE -> VER-AGE:AGE:REV)
ensures different sonames in any case.

src/Makefile.am

@@ -176,7 +176,7 @@ libvlccore_la_CFLAGS = `$(VLC_CONFIG) --cflags libvlccore` \
 libvlccore_la_LDFLAGS = `$(VLC_CONFIG) --ldflags libvlccore` $(AM_LDFLAGS) \
 	-no-undefined \
 	-export-symbols $(srcdir)/libvlccore.sym \
-	-version-info 3:0:0
+	-version-info 4:0:0
 libvlccore_la_LIBADD = `$(VLC_CONFIG) -libs libvlccore` $(AM_LIBADD) \
 	$(LTLIBINTL) ../compat/libcompat.la
 libvlccore_la_DEPENDENCIES = libvlccore.sym