Fix minimum required version for the dependency dev-libs/boehm-gc.
This was already required by the configure script, so it does not
affect the stable status.
Closes: https://bugs.gentoo.org/602384
Package-Manager: Portage-2.3.15, Repoman-2.3.5
>=dev-cpp/glibmm-2.48
>=dev-cpp/gtkmm-2.18.0:2.4
>=dev-cpp/cairomm-1.9.8
- >=dev-libs/boehm-gc-6.4
+ >=dev-libs/boehm-gc-7.1
>=dev-libs/glib-2.28
>=dev-libs/libsigc++-2.0.12
>=dev-libs/libxml2-2.6.20
>=dev-cpp/glibmm-2.48
>=dev-cpp/gtkmm-2.18.0:2.4
>=dev-cpp/cairomm-1.9.8
- >=dev-libs/boehm-gc-6.4
+ >=dev-libs/boehm-gc-7.1
>=dev-libs/glib-2.28
>=dev-libs/libsigc++-2.0.12
>=dev-libs/libxml2-2.6.20
>=dev-cpp/glibmm-2.48
>=dev-cpp/gtkmm-2.18.0:2.4
>=dev-cpp/cairomm-1.9.8
- >=dev-libs/boehm-gc-6.4
+ >=dev-libs/boehm-gc-7.1
>=dev-libs/glib-2.28
>=dev-libs/libsigc++-2.0.12
>=dev-libs/libxml2-2.6.20