vm: Retire vm_page_alloc_freelist{,_domain}()

[alc]

Summary

Once upon a time, I created vm_page_alloc_freelist{,_domain}() to support faster allocation of pages that were mapped by the partial direct map on 32-bit MIPS. At the time, I expected that these functions might find other uses too, but those other uses never materialized. So, these functions have not been used for some time now. Instead, people use the more general vm_page_alloc_contig().

[markj]

The removed functions are also documented in share/man/man9/vm_page_alloc.9 (and have MLINKS in share/man/man9/Makefile).

[alc]

Update man page.