Make debug_info rules clear

[ferd]

Current rebar3 uses debug_info rules where debug_info is added by
default, and no_debug_info prevents the default from being added, and
removes any explicit debug_info, if any. The problem is that if
'no_debug_info' is anywhere in the config for a run, it cannot be
removed even with other profiles. additionally, no_debug_info ignores
special tuples like {debug_info, {Mod, Data}} and {debug_info_key, Key},
which can be used to add debug info and encrypt it (in lieu of plain
debug_info) respectively.

This patch makes it so that the following rules are in place:

• the first option seen takes priority, allowing profile overrides by
  the ordering rules
• because the compiler apparently does not care for that order (it does
  not have to), the overriden options shall be explicitly deleted
• any option related to debug info seen first cancels any no_debug_info
  that follows
• any no_debug_info option seen first cancels all of the other
  debug_info options
• if debug_info is seen first, it cancels out {debug_info_key, Key}
• if {debug_info_key, Key} is seen first, it cancels out debug_info
• All other options are left untouched in that context (defines can
  still be expanded and so on)

This should allow proper profile rules to be followed. See #1653 for context.

[ferd]

Interesting. I still get the failures in CI. Will have to also investigate that one further.

[bitnitdit]

@ferd , the change looks good to me. Thanks!

[ferd]

I found the problem; erl_opts are specifically merged in the profile-order so that if you go rebar3 as a,b,c compile, the options from profile A come before B, which come before C, because that's how the compiler handles them. My PR right here assumed they were being merged like other keys (C > B > A) to give proplist preference.

I'll rework the PR so it's done on the right direction.