LU-8028 build: fix make dependencies for --disable-modules

LU-8028 build: fix make dependencies for --disable-modules

When modules are excluded from a build there is no rule to build undef.h.
As result build fails with following:
/usr/include/stdc-predef.h:40:1: fatal error:
        /work/lustre-release/undef.h: No such file or directory

Test-Parameters: trivial
Change-Id: I4bf031933964c7d11f9e1c4a88016e1827d11762
Signed-off-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-on: https://review.whamcloud.com/30965
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>