mcdb_makefn - add comment for diff from mcdb_make
mcdb_makefn - add comment for diff from mcdb_make

mcdb_makefn - add comment for difference between mcdb_makefn_finish()
and mcdb_make_finish().  mcdb_makefn_finish() does not call
mcdb_makefn_cleanup() so that callers, e.g. Python, can release some
locks during the potentially lengthy fsync of mcdb to disk

gstrauss/mcdb,gstrauss/mcdb,gstrauss/mcdb,gstrauss/mcdb,gstrauss/mcdb