Add CTRL interface to osmo-mgw

OsmoMGW has a lot of nice built-in statistics (rate_ctr,...) but it
seems the only way to look at them is via the VTY. While libosmocore
contains automatic exposure of all rate counters via CTRL, the CTRL
interface simply is not used by osmo-mgw so far.

Closes: OS#4441
Change-Id: I7ed6bdb9f4749c24ca11a5905a620546cfe42952
diff --git a/configure.ac b/configure.ac
index c74526b..880a756 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,6 +41,7 @@
 
 PKG_CHECK_MODULES(LIBOSMOCORE, libosmocore >= 1.1.0)
 PKG_CHECK_MODULES(LIBOSMOGSM, libosmogsm >= 1.1.0)
+PKG_CHECK_MODULES(LIBOSMOCTRL, libosmoctrl >= 1.1.0)
 PKG_CHECK_MODULES(LIBOSMOVTY, libosmovty >= 1.1.0)
 PKG_CHECK_MODULES(LIBOSMONETIF, libosmo-netif >= 0.6.0)