[Bug debug/95096] New: Feature request: add -fsplit-dwarf

[i at maskray dot me]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95096

            Bug ID: 95096
           Summary: Feature request: add -fsplit-dwarf
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: i at maskray dot me
  Target Milestone: ---

-gsplit-dwarf has an undesired property: it sets the debug info level to 2.
When plugged into a build system, this can enable debug info unnecessarily
(when the user does not specify -g or specifies -g0).

-fsplit-dwarf can enable .dwo, but do not enable debug info by itself.

Its reaction with -g1 may need some thoughts: whether line tables in .dwo will
be beneficial. As a start, we can add the option first, which should be simple
(for a beginner like me:/ )