Correct the default Bazel vector instructions options

[mhucka]

The documented way that bazel build, bazel test, and similar commands behave without options like --config=avx is that the AVX, SSE, and other optimization options are not applied. However, this was not what was happening: the default ended up applying them even if --config=sse etc. were not used. Evidently, the previous changes to .bazelrc and dev_tools/test_libs.sh that I did in PR #758 and other recent PRs not correct this.

The changes here invert the way --build_tag_filters and --test_tag_filters are used: they are set to filter out things tagged with avx and sse by default in .bazelrc, and options like --config=sse add the things back.

To make this work, dev_tools/test_libs.sh has to be updated as well.

[pavoljuhas]

This runs into the same problem as in #710 - the shell has the -e option so the script will exit here if any of avx2 or sse features were missing. To have a positive condition, you need to rewrite this as

if [[ "$features" == *avx2* ]]; then
    filters+=",avx"
fi
...

[mhucka]

So, I tested the following, and it does not exit early. Do you have an environment where it doesn't work this way?

 #!/usr/bin/env bash

 set -eo pipefail -o errtrace

 declare foo=""
 declare bar="original"

 foo="something"
 [[ "$foo" == *notthere* ]] && bar="new string"

 echo $bar

[pavoljuhas]

I stand corrected - per bash set -e doc for the && and || lists it is only the last command that counts for errexit. I got confused, because on my Debian box it indeed exits early in an interactive session. This happens because interactive bash runs some fancy prompt functions which try to restore the exit status of the last command and that triggers errexit.

With your snippet (and the same system bashrc) this can be reproduced with

bash -i <snippet.bash

TLDR - it is OK as is.

[mhucka]

Wow, that's unobvious. Thanks for the info!

[pavoljuhas]

test_libs.sh may exit too early, please correct.