community/duperemove: fix build with gcc 14 on 32-bit arches

Fix -Wincompatible-pointer-types error with gcc 14 on 32-bit arches, found on the 3.21 armv7 builder (error log).

run_dedupe.c: In function 'add_shared_extents_post':
run_dedupe.c:161:44: error: passing argument 4 of 'fiemap_count_shared'
from incompatible pointer type [-Wincompatible-pointer-types]
  161 |                                            &bytes);
      |                                            ^~~~~~
      |                                            |
      |                                            uint64_t * {aka long long unsigned int *}
In file included from run_dedupe.c:42:
fiemap.h:29:75: note: expected 'size_t *' {aka 'unsigned int *'} but
argument is of type 'uint64_t *' {aka 'long long unsigned int *'}
   29 | int fiemap_count_shared(int fd, size_t start_off, size_t end_off, size_t *shared);