LU-987 build: Fail to create ldisk rpms

LU-987 build: Fail to create ldisk rpms

The autoMakefile.am in ldsikfs does not define the
BUILD_SERVER flag so make rpms fails. This patch
simply set the flag to true since ldiskfs will most
likely be used only on servers
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Change-Id: Ic42eb543658f97bbff9c2f360d8693da840a8a36
Reviewed-on: http://review.whamcloud.com/2113
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>