Change macOS mmap tag to fix conflict with IOAccelerator

[kdrag0n]

Tag 100 is assigned to "IOAccelerator" (the GPU driver stack on Apple silicon), which makes for confusing output when debugging.

To avoid conflicts, use a tag in the reserved application-specific range from 240–255 (inclusive).

All assigned tags: https://github.com/apple-oss-distributions/xnu/blob/94d3b452840153a99b38a3a9659680b2a006908e/osfmk/mach/vm_statistics.h#L773-L775