Adjust "./Configure" for wider architecture support

[tianon]

This builds on #38, and adds an appropriate -Darchname value for cross-building (arm32v7 builds on an arm64v8 kernel, i386 builds on an amd64 kernel, etc), and conditionally converts -Duse64bitall into -Duse64bitint (which is what Debian uses when compiling Perl).

*** You have chosen a maximally 64-bit build,
*** but your pointers are only 4 bytes wide.
*** Please rerun Configure without -Duse64bitall.
*** Since you have quads, you could possibly try with -Duse64bitint.

See also https://sources.debian.net/src/perl/stretch/debian/config.debian/#L115 and https://sources.debian.net/src/perl/stretch/debian/config.debian/#L130.

    -Darchname=$host_gnu_type			\
...
    -Duse64bitint                               \

I've personally tested (successfully) building 5.026.000-64bit/Dockerfile on arm32v7, arm64v8, i386, s390x, and ppc64le. I'm happy to perform further testing as desired. This should really work fine on any of the architectures supported by buildpack-deps:stretch (amd64, arm32v5, arm32v7, arm64v8, i386, ppc64le, s390x), although I haven't verified arm32v5 directly (since it has no hardware floating point, and thus is usually really slow 😅).

[tianon]

Might be worth noting that this requires docker-library/buildpack-deps#65 as-is, which was merged to official-images over in docker-library/official-images#3378.

[zakame]

@tianon nice work! Yeah I remember dpkg-architecture, very useful on Debian/Ubuntu packaging work (I was a MOTU before.) I was already mulling on doing build support for i386, arm32v7 et al. but you beat me to it 💃

[zakame]

I suppose we ought to change the 64bit names here now to something else (maybe std,) since we can build 32- or 64-bit depending on dpkg-architecture.

[tianon]

😇 definitely didn't intend to steal your thunder! I won't be offended at all if you redo this outright or just want to take over, but I'm also happy to help, adjust etc as much as you'd like me to. 👍

[zakame]

Haha no worries, no offense taken at all! :D

[zakame]

@tianon how would I go about testing this on my own? Say, I want to try building 32-bit Perl 5.22 and 5.24 on amd64. I was looking at https://doi-janky.infosiftr.net/job/multiarch/ but can't make out the process (probably not looking hard enough...)

[yosifkit]

The build server does something like the following.

$ docker pull i386/buildpack-deps:stretch 
$ docker tag i386/buildpack-deps:stretch buildpack-deps:stretch
$ docker build -t image-name .

An example from travis build for memcached.

That will most likely interfere with other images you build on the same machine. You can accomplish the same thing by temporarily changing the FROM in the Dockerfile to i386/buildpack-deps:stretch (or the proper parent) and doing a docker build.

[zakame]

@yosifkit thanks, it is similar to how I tested for #38 :) Will try it on a spare machine/VM.

[zakame]

Thanks @tianon @yosifkit for the help, I'm able try building 32-bit Perls 5.22 through 5.26 on amd64, and I'll take @tianon's word about the other archs he has already tested. :)

I'll adjust this after merging to rename some paths to the Dockerfiles as hinted in #43 (comment); many thanks again!