xfsdump: don't try to generate .ltdep in inventory/

.ltdep gets generated from CFILES, and there are none in inventory/
so trying to generate it in that dir leads to a non-fatal error:

Building inventory
    [LTDEP]
gcc: fatal error: no input files
compilation terminated.

inventory/ - like common/ - has files that get linked into other dirs,
and .ltdep is generated there.  So, simply remove the .ltdep generation
from the inventory/ dir.

Reported-by: Thomas Deutschmann <whissi@gentoo.org>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Bill O'Donnell <billodo@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/inventory/Makefile b/inventory/Makefile
index cda145e..6624fba 100644
--- a/inventory/Makefile
+++ b/inventory/Makefile
@@ -12,5 +12,3 @@
 default install install-dev:
 
 include $(BUILDRULES)
-
--include .ltdep