Testing and outstanding issues

[Torbjörn Granlund]

Various things has slowed down testing on the main machine ("martin")
lately making it 100% loaded 20 hours each day.  Now I implemented
splitting of the testing burden over three days.  Furthermore, shell
will no longer run any tests.

This static testing is reaching its limits.  I have a beginning of a
change driven mechanism instead, queuing snapshots for testing, using
some heuristics about which config should be run.  (E.g., a change in
mpn/foo/addmul_1.asm will run foo systems but not run bar systems.)

I added not just ubsan but also asan testing.  These tests triggered
bugs in the acinclude.m4 tests, requiring some minor edits.  No asan has
run yet, but ubsan resulted on a few errors, see
https://gmplib.org/devel/tm/gmp/date.html.

If we decide to make a 6.1.2, we should clean up ubsan and asan errors
in that repo too before releasing.  (The reporting mechanism supports
keeping separate result pages since some time; directing the test
systems to another repo is a one line edit in a script.)

-- 
Torbjörn
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