Depend on liboping 1.7.0 instead of 1.9.0

Debian8 provides 1.7.0. Let's depend on it so we can build packages for
debian8.

Change-Id: Idba4494102d48d125bcd215dd0d3fdf42bbd409e

configure.ac

@@ -45,7 +45,8 @@ PKG_CHECK_MODULES(LIBOSMOGSM, libosmogsm >= 0.11.0)
 PKG_CHECK_MODULES(LIBOSMONETIF, libosmo-netif >= 0.4.0)
 PKG_CHECK_MODULES(LIBMNL, libmnl)
 dnl FIXME: bump to 1.10.0 once it's available on build slaves and remove workaround from osysmon_ping.c
-PKG_CHECK_MODULES(LIBOPING, liboping >= 1.9.0)
+dnl FIXME: debian8 provides 1.7.0, debian9 provides 1.9.0
+PKG_CHECK_MODULES(LIBOPING, liboping >= 1.7.0)
 
 dnl checks for header files
 AC_HEADER_STDC

debian/control

@@ -11,7 +11,7 @@ Build-Depends: debhelper (>=9),
                pkg-config,
                libtalloc-dev,
                libmnl-dev,
-               liboping-dev (>= 1.9.0),
+               liboping-dev (>= 1.7.0),
                libosmocore-dev (>= 1.0.1),
                libosmo-netif-dev (>= 0.4.0),
 Standards-Version: 3.9.8