mdbx: fix unexpected SIGBUS is not enough space in a filesystem.

On a modern Linux the allocation of space for a file can be deferred
and/or lazy, rather than when setting its length using `ftruncate()`.
The actual allocation of space occurs when writing to the corresponding
areas of the file, or when reading ones (in this case, the file system
fills these areas with zeros).

The specific behavior depends on the type of file system and the kernel
version, but the main thing is that possibilities currently are, when
setting the file size, just the instantaneous ability to allocate space
is checked, without any booking.

If the file system is running out of space, an `ENOSPC` error may occur
when processing (inside a OS kernel) a page fault when accessing one of
the added pages after the database has been enlarged. In this case, the
OS kernel has no other alternative but to send a `SIGBUS` signal to the
process.

This commit fixes the problem by adding the use of system calls to
explicitly allocate space for a given file size.
Related-to https://github.com/erigontech/erigon/issues/16709

This is a simple improvement, however which is complicated by the need
to take into account the availability of the appropriate system API and
handle non-fatal errors from file systems that do not support the
appropriate operations. Therefore, there is a risk of regressions in
unusual/rare situations, including when hosting databases on network
media.

src/lck.c

@@ -62,9 +62,9 @@ __cold static int lck_setup_locked(MDBX_env *env) {
   }
   env->max_readers = (maxreaders <= MDBX_READERS_LIMIT) ? (unsigned)maxreaders : (unsigned)MDBX_READERS_LIMIT;
 
-  err =
-      osal_mmap((env->flags & MDBX_EXCLUSIVE) | MDBX_WRITEMAP, &env->lck_mmap, (size_t)size, (size_t)size,
-                lck_seize_rc ? MMAP_OPTION_TRUNCATE | MMAP_OPTION_SEMAPHORE : MMAP_OPTION_SEMAPHORE, env->pathname.lck);
+  err = osal_mmap((env->flags & MDBX_EXCLUSIVE) | MDBX_WRITEMAP, &env->lck_mmap, (size_t)size, (size_t)size,
+                  lck_seize_rc ? MMAP_OPTION_SETLENGTH | MMAP_OPTION_SEMAPHORE : MMAP_OPTION_SEMAPHORE,
+                  env->pathname.lck);
   if (unlikely(err != MDBX_SUCCESS))
     return err;