Turn libosmo-mgcp into local, non-installed library

This is an internal library simmilar to 'libmsc' in osmo-msc, which
we don't expect to be used by other programs except osmo-mgw.  Hence,
there's no need to install it as a shared library, which introduces
requirements about ABI/API stability and the like.

osmo-bsc_nat uses libosmo-legacy-mgcp, and once we should rewrite
osmo-bsc_nat, we might need some of the libosmo-mgcp related functions,
but at this point it's unclear what exactly would be needed and if
current libosmo-mgcp can provide that.  As needed, we can introduce
a related shared library at that point.

Change-Id: Iba0a2c9c694e360356ac2ca584e97795281c6198
diff --git a/debian/control b/debian/control
index e96115f..383a35a 100644
--- a/debian/control
+++ b/debian/control
@@ -16,23 +16,8 @@
 Package: osmo-mgw
 Architecture: any
 Multi-Arch: foreign
-Depends: libosmo-mgcp1, ${misc:Depends}, ${shlibs:Depends}
-Description: OsmoMGW: Osmocom's Media Gateway for 2G and 3G circuit-switched mobile networks
-
-Package: libosmo-mgcp1
-Section: libs
-Architecture: any
-Multi-Arch: same
-Pre-Depends: ${misc:Pre-Depends}
 Depends: ${misc:Depends}, ${shlibs:Depends}
-Description: libosmo-mgcp: Osmocom's Media Gateway server library
-
-Package: libosmo-mgcp-dev
-Section: libdevel
-Architecture: any
-Multi-Arch: same
-Depends: libosmo-mgcp1 (= ${binary:Version}), ${misc:Depends}
-Description: libosmo-mgcp: Osmocom's Media Gateway server library
+Description: OsmoMGW: Osmocom's Media Gateway for 2G and 3G circuit-switched mobile networks
 
 Package: libosmo-mgcp-client2
 Section: libs