mdbx: partial fix for recursive SRW-lock with MDBX_NOTLS on Windows.

Here are some changes to avoid recursive acquisition of SRW-lock,
which is still in use:
 - Read transactions don't acquire the shared SRW-lock with `MDBX_NOTLS.
 - Memory-mapping of DB is always kept while DB opened,
   therefore following limitations are:
 - DB file can't be shrinked while it used,
   including auto-shrink due to auto-compactification with corresponding geometry settings.
 - The upper limit of DB size can't be changed while DB is used.
 - The DB can grow within the upper size limit defined while opening by a first process,
   but this does not work under Wine since there is no `NtExtendSection()` function.

Partially fix https://github.com/erthink/libmdbx/issues/203

src/osal.h

@@ -695,8 +695,10 @@ MDBX_INTERNAL_FUNC int mdbx_mmap(const int flags, mdbx_mmap_t *map,
                                  const size_t must, const size_t limit,
                                  const unsigned options);
 MDBX_INTERNAL_FUNC int mdbx_munmap(mdbx_mmap_t *map);
-MDBX_INTERNAL_FUNC int mdbx_mresize(int flags, mdbx_mmap_t *map, size_t current,
-                                    size_t wanna, const bool may_move);
+#define MDBX_MRESIZE_MAY_MOVE 0x00000100
+#define MDBX_MRESIZE_MAY_UNMAP 0x00000200
+MDBX_INTERNAL_FUNC int mdbx_mresize(const int flags, mdbx_mmap_t *map,
+                                    size_t size, size_t limit);
 #if defined(_WIN32) || defined(_WIN64)
 typedef struct {
   unsigned limit, count;