Clean up cluster lock mode and flags definition.

Clean up cluster lock mode and flags definition.

Code is mixing up internal DLM and LVM definitions of lock
modes and flags.

OpenAIS and singlenode locking do not depend on DLM but
code currently cannot be compiled without libdlm.h!

LCK_* flags is LVM abstraction, used through all the code.
Only low-level backend (clvmd-cman etc) should use DLM definitions,
also this code should do all needed conversions.

Because there are two DLM flags used in generic code
(NOQUEUE, CONVERT) we define it similar way like lock modes.
(So all needed binary-compatible flags are on one place in locking.h)

(Further code cleaning still needed, though:-)