LU-1972 mdt: declare RPC handlers in a sane way

LU-1972 mdt: declare RPC handlers in a sane way

Declare the MDT RPC handlers in a way that they can be found when
searching for them, otherwise the code is completely opaque when
looking for the handler for an RPC (e.g. MDS_CLOSE or LDLM_ENQUEUE).

While it might make sense to have macros replace a lot of repetetive
code blocks, it doesn't make sense to chop up the RPC names so badly
that they can never be found through normal searching.  Rename the
RPC handler definition macros to have more meaningful names, and
remove unused macros and special cases where not strictly necessary.

Rename a few OBD_FAIL_LDLM_ error injection hooks instead of making
the macros more complex for a small number of use cases.  These names
are only used internally, even if the values are used in the tests.

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I8d4dc0709faeae4458c3563864268a00f8500c1e
Reviewed-on: http://review.whamcloud.com/4260
Tested-by: Hudson
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Mike Pershin <tappro@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>