Bug#833846: fflas-ffpack: don't generate optimised code based on the build machine

[Ximin Luo]

Package: fflas-ffpack
Version: 2.2.1-1
Severity: important

Dear Maintainer,

fflas-ffpack on amd64 was built with "-msse4.1 -mfma -mavx2" as can be seen
from the output of `pkg-config --cflags fflas-ffpack`. This unfortunately makes
it crash on amd64 machines that don't support these instructions, and we are
running into this issue whilst testing SageMath.

Please disable any build options that set optimisations based on autodetection
of the CPU features of the build machine.

It should be OK to hard-code "-mmmx -msse -msse2" for amd64 and "-msse -msse2"
for i386, according to wRAR on #debian-devel. This is somewhat based on
information from [1]. There might be other optimisations you can make, but I
haven't yet done the detailed research for that.

X

[1] https://lists.debian.org/debian-devel-announce/2016/05/msg00001.html

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'stable'), (300, 'unstable'), (200, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.6.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages fflas-ffpack depends on:
ii  fflas-ffpack-common  2.2.1-1

fflas-ffpack recommends no packages.

Versions of packages fflas-ffpack suggests:
pn  fflas-ffpack-dev-doc   <none>
pn  fflas-ffpack-user-doc  <none>

-- no debconf information