Compile jemalloc with 16 KiB page size on arm

[Diatrus]

This is needed for kernels with 16 KiB page sizes (currently the kernel for the Apple M1).
This was tested on a 16 KiB kernel does not cause any functionality regression.

See the following discussion for why page size must be set higher or equal to expected:
jemalloc/jemalloc#467 (comment)

[kmihelich]

How about on a 4k kernel? Everything here is currently 4k.

[Diatrus]

How about on a 4k kernel? Everything here is currently 4k.

According to the linked comment and subsequent reading of the actual configure argument, it should work on 4K. However, I do not personally have a device that currently supports a 4 KiB page size kernel and would appreciate help with a proper test in that regard.

[Diatrus]

@kmihelich I have decreased the compiled page size to 16 KiB, as I would say it’s unlikely ALARM will ship a 64 KiB kernel anytime soon. I can squash later if need-be.

[jannau]

Using jemalloc compiled for a larger page size than the system's page size is not problem. rust with static copy of jemalloc work with this patch changing the page size to 64k on systems with 4k and 16k kernel page size without problems.

[leifliddy]

So it looks like Fedora sorted out this issue the same way four years ago by including the following logic in their version of a PKGBUILD

# Override PAGESIZE, bz #1545539
%ifarch %ix86 %arm x86_64 s390x
%define lg_page --with-lg-page=12
%endif

%ifarch ppc64 ppc64le aarch64
%define lg_page --with-lg-page=16
%endif

https://bugzilla.redhat.com/show_bug.cgi?id=1545539