libmdbx: pull from https://github.com/leo-yuriev/libmdbx (MDBX_KEYEXIST for MDBX_APPEND+MDBX_NOOVERWRITE).

This resolves #141

Merge commit '02fc5fe1585599a0df45608d53c15c440685ce89' into devel

Author: erthink

libraries/libmdbx/src/mdbx.c

@@ -7195,7 +7195,8 @@ int mdbx_cursor_put(MDBX_cursor *mc, MDBX_val *key, MDBX_val *data,
     } else {
       rc = mdbx_cursor_set(mc, key, &d2, MDBX_SET, &exact);
     }
-    if ((flags & MDBX_NOOVERWRITE) && rc == 0) {
+    if ((flags & MDBX_NOOVERWRITE) &&
+        (rc == MDBX_SUCCESS || rc == MDBX_EKEYMISMATCH)) {
       mdbx_debug("duplicate key [%s]", DKEY(key));
       *data = d2;
       return MDBX_KEYEXIST;

libraries/libmdbx/src/version.c

@@ -18,8 +18,8 @@
 #error "API version mismatch!"
 #endif
 
-#define MDBX_VERSION_RELEASE 0
-#define MDBX_VERSION_REVISION 0
+#define MDBX_VERSION_RELEASE 2
+#define MDBX_VERSION_REVISION 1
 
 /*LIBMDBX_EXPORTS*/ const mdbx_version_info mdbx_version = {
     MDBX_VERSION_MAJOR,