Fix broken parallel install

There is an automake bug when using _LTLIBRARIES, breaking parallel
`make install` (see http://debbugs.gnu.org/cgi/bugreport.cgi?bug=7328)

BUG: 981888
Change-Id: Ib35ae47c048a45a881aeb9dbf8d41e09a4e766b9
Signed-off-by: Tiziano Müller <tiziano.mueller@stepping-stone.ch>
Reviewed-on: http://review.gluster.org/5468
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>