[3.12] gh-113343: Fix error check on mmap(2) (GH-113342) (#113374)

[3.12] gh-113343: Fix error check on mmap(2) (GH-113342) (#113374)

gh-113343: Fix error check on mmap(2) (GH-113342)

Fix error check on mmap(2)

It should check MAP_FAILED instead of NULL for error.

On mmap(2) man page:

  RETURN VALUE
       On success, mmap() returns a pointer to the mapped area.
       On error, the value MAP_FAILED (that is, (void *) -1) is
       returned, and errno is set to indicate the error.
(cherry picked from commit 6b70c3dc5ab2f290fcdbe474bcb7d6fdf29eae4c)

Co-authored-by: Namhyung Kim <namhyung@gmail.com>