cmake: link ceph-{mds,mgr,mon,osd} against libcommon
add a static library named global-static, which does not link with
libceph-common. so the executables which does not link against
lib{rados,cephfs,rbd} can be linked against global-static instead if
they want to access the symbols previously available from libglobal.
and libglobal is now linked against libceph-common. and it is supposed
to be used by executables packaged by ceph-test. these exectuables can
safely depend on libceph-common offered by package of "librados2".