cockpit-deps: Fix libssh devel package to require its dependencies

This fixes the libssh-rc-devel package for fedora-20 to pull devel dependencies. Changes are actually:

+Requires:       openssl-devel
+Requires:       zlib-devel
+Requires:       krb5-devel

and:
 
-       -e 's|-lssh|-lz -lcrypto -lkrb5 -lgssapi_krb5 %{_libdir}/libssh_rc.a|' \
+       -e 's|-lssh|-lz -lcrypto -lkrb5 -lgssapi_krb5 -lrt %{_libdir}/libssh_rc.a|' \