fix test_unit with gcc-15 / use standard uint* instead of u_int

[PPN-SD]

fix test_unit:

tests/test_unit.c:152:9: error: use of undeclared identifier 'uintptr_t'; did
you mean 'intptr_t'?
152 | assert_null(media_data);

tests/test_unit.c: In function ‘main’:
tests/test_unit.c:297:30: error: initialization of ‘void ()(void **)’
from incompatible pointer type ‘void ()(void)’ [-Wincompatible-pointer-types]
297 | cmocka_unit_test(test_correct_media_drivers_for_mediatype_count)

use uint*, thus fix building w/ musl:

image.c:466:5: error: unknown type name 'u_int32_t'; did you mean 'uint32_t'?
466 | u_int32_t current_box_len = __bswap_32(((u_int32_t) avifhdr));
| ^~~~~~~~~
| uint32_t