libmdbx: switch to original amalgamated source code (v0.9.1.18)

Amalgamated source code is the recommended form for
embedding libmdbx in non-CMake build systems. This amalgamated
version contains a minimum of files, is fully ready for use,
and make impossible a number of errors.

To upgrade or switch to a different version, just unpack
to the `src` subdirectory a corresponding `libmdbx-amalgamated-X_Y_Z.zip`
at the https://github.com/erthink/libmdbx/releases.

For instance, the https://github.com/erthink/libmdbx/releases/download/v0.9.2/libmdbx-amalgamated-0_9_2.zip
for the next release.

--

Minimal changes have been made to the build configuration:

1. For use the standard `DllMain()` entry of libmdbx:
   - added the `MDBX_BUILD_SHARED_LIBRARY=1` option;
   - removed the `MDBX_CONFIG_MANUAL_TLS_CALLBACK` option;
   - deleted the `miranda.c` file containing only `DllMain()`
     with the `mdbx_dll_handle()` call, now this is done by the library itself.

2. Removed refs to extra files (that missing in the amalgamated source code):
   - for building `libmdbx.dll` only the `mdbx.h` and `mdbx.c` are used,
     but not `mdbx.c++` for a C++ API;
   - for building the `mdbx_chk`, `mdbx_load`, and `mdbx_dump` utilities
     only it own sources are used.

--

Last libmdbx changes:

 - Fixed missing installation of `mdbx.h++`.
 - Fixed use of obsolete `__noreturn`.
 - Fixed use of `yield` instruction on ARM if unsupported.
 - Added pthread workaround for buggy toolchain/cmake/buildroot.
 - Fixed use of `pthread_yield()` for non-GLIBC.
 - Fixed use of `RegGetValueA()` on Windows 2000/XP.
 - Fixed use of `GetTickCount64()` on Windows 2000/XP.
 - Fixed opening DB on a network shares (in the exclusive mode).
 - Fixed copy&paste typos.
 - Fixed minor false-positive GCC warning.

1 files changed, 0 insertions, 22 deletions

diff --git a/libs/libmdbx/src/COPYRIGHT b/libs/libmdbx/src/COPYRIGHT
deleted file mode 100644
index fc6d9eed24..0000000000
--- a/libs/libmdbx/src/COPYRIGHT
+++ /dev/null
@@ -1,22 +0,0 @@
-Copyright 2015-2020 Leonid Yuriev <leo@yuriev.ru>.
-Copyright 2011-2015 Howard Chu, Symas Corp.
-Copyright 2015,2016 Peter-Service R&D LLC.
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted only as authorized by the OpenLDAP
-Public License.
-
-A copy of this license is available in the file LICENSE in the
-top-level directory of the distribution or, alternatively, at
-<http://www.OpenLDAP.org/license.html>.
-
-OpenLDAP is a registered trademark of the OpenLDAP Foundation.
-
-Individual files and/or contributed packages may be copyright by
-other parties and/or subject to additional restrictions.
-
-This work also contains materials derived from public sources.
-
-Additional information about OpenLDAP can be obtained at
-<http://www.openldap.org/>.