[Bug diagnostics/124159] Add -Wbogus warning class

[siddhesh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124159

--- Comment #3 from Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> ---
Based on reported bugs, -Wdangling-pointer doesn't seem as noisy as
-Wstringop-* or -Warray-bounds and they all either point to warnings on dead
code or missed optimization.

I personally don't like the idea of a killswitch for these warnings though;
while they're noisy, they have been *very* useful.  It will incorrectly
encourage users to disable all warnings even if they're not problematic on
their code base.