cmake: remove unnecessary linked libs from libcephfs
* some of the libs shares the same .cc which has static C++ variables. if
we link against the different libs sharing the same static C++
variables, and the dtor of the C++ variables has side-effects, among
other things, deallocates a memory chunk. then, we are in the trouble of
double free. so "osd" lib is removed.
* some of the libs are referenced by the linked lib, so no need to link
against them again. for example, BLKID_LIBRARIES are linked by
libcommon, so we can remove it from the linked libs list.
* and lib "os" and "cls_references_objs" are not used by libcephfs at all,
so remove them.