(ITS#8483) CMake buildsystem support for LMDB

[intelfx@intelfx.name]

Full_Name: Ivan Shapovalov
Version: LMDB 0.9.18
OS: GNU/Linux
URL: ftp://ftp.openldap.org/incoming/ivan-shapovalov-160820.patch
Submission from: (NULL) (77.41.63.43)


This patch adds a CMake buildsystem for LMDB, side-by-side with existing
Makefile.
It builds the same targets except coverage tests.

Rationale for this change: CMake simplifies building of LMDB with non-standard
toolchains
such as Android NDK which only support their custom buildsystem and CMake (via
a
provided CMake toolchain configuration file).
This way, one does not need to extract required compiler flags manually.
Moreover, this simplifies life for projects which use CMake and LMDB, because a
proper CMake buildsystem allows to e. g. automatically pass transitive
dependencies like pthreads to dependent projects.