LU-4998 lustre: unpackage several headers

Remove lustre_idl.h, libiam.h and lustre_lfsck_user.h from the list of
packaged headers. Move conf-sanity 74a (checking that Lustre client
api program can compile and link) to sanity 400a. Add sanity 400b to
check that the headers installed in /usr/include/lustre/ (with the
exception liblustreapi.h) can be compiled without warning.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Change-Id: I0e99e3e0d18907488f2f8c94e33c58990262ee8a
Reviewed-on: http://review.whamcloud.com/10215
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-by: Robert Read <robert.read@intel.com>
New tag 2.5.59

Change-Id: Ifcb48b768cec2216939ce7ee70b1339b71f62358