make: handle blacklisted features separately from missing requirements

[aabadie]

Contribution description

This PR addresses the several comments (#9081 (comment), #9081 (comment)) made in #9081 but kept unadressed about moving the management of blacklisted features in a dedicated variable.

The current behavior is to say a blacklisted features used is a missing non blacklisted requirements. This is far from obvious.

We can discuss on the name of the new variable introduced by this PR. But at least the error message displayed when one wants to use a blacklisted feature in an application is much more easy to understand.

Testing procedure

• make info-board-supported should not differ from master
• A green CI is also a good indicator

Issues/PRs references

Cleanup of #9081

[fjmolinas]

Thanks a lot for addressing this @aabadie. Some minor naming comment's,

I also think it would be good to have a variable that aggregates FEATURES_BLACKLISTED and FEATURES_MISSING, something like FEATURES_REQUIREMENTS_MISSING

[fjmolinas]

Suggested change

	# Having blacklisted features may case the build to fail.
	# Having blacklisted features may cause the build to fail.

[fjmolinas]

This should be FEATURES_USED_BLACKLISTED

[aabadie]

I also think it would be good to have a variable that aggregates FEATURES_BLACKLISTED and FEATURES_MISSING, something like FEATURES_REQUIREMENTS_MISSING

I don't think so. We will go back to the double negation crappy thing that this PR is trying to avoid.

[fjmolinas]

I don't think so. We will go back to the double negation crappy thing that this PR is trying to avoid.

True!

[aabadie]

True!

May I squash ?

[fjmolinas]

The double negation is no longer present, can you also add FEATURES_USED_BLACKLISTED to info-build

FEATURES_MISSING (only non optional features):
         -none-
FEATURES_BLACKLIST (blacklisted features):
         arch_esp8266

Otherwise I ran the following testing procedure after rebasing on master.

for app in $(make info-applications); do echo "$app"; make --no-print-directory -C ${app} info-boards-supported;echo " "; done > [pr12453/master].txt

diff pr12453.txt master.txt
# no diff

If you agree with my change suggestion squash immediatly.

[aabadie]

If you agree with my change suggestion squash immediatly.

Done

[fjmolinas]

ACK, lets see what murdock says.

[aabadie]

lets see what murdock says.

Murdock agrees