compiling with new version of LMDB

[kroggen]

Some updates in the code to make it able to be compiled against the LMDB version currently available on GitHub.

Although I am not sure about the LOCKSUFF stuff.

[kroggen]

The reason I replaced the

#define MDB_USE_HASH	1

by

#ifndef _WIN32
#define MDB_USE_POSIX_SEM  1
#endif

is because of the function mdb_env_mname_init() that uses the env->me_mutexname and this one is only present when _WIN32 or MDB_USE_POSIX_SEM is defined.

An optional approach would be using some ifdefs around the mdb_env_mname_init() function and the #MUTEXNAME() on mdb.c.

[derrickgreenspan]

Thank you so much. You have saved me a lot of grief getting sqlightning working with LMDB.