Adds SIGNAL_HANDLER, a macro that sets SHOULD_NOT_SLEEP(TRUE). This should ideally be required on all new signal callbacks.
Adds BLOCKING_SIGNAL_HANDLER, a macro that does nothing except symbolize "this is an older signal that didn't necessitate a code rewrite". It should not be allowed for new work.
This comes from discussion around #52735, which yields by calling input, and (though it sets the return type beforehand) will not properly return the flag to prevent attack from slapping.
To fix 60% of the yielding cases, WrapAdminProcCall no longer waits for another admin's proc call to finish. I'm not an admin, so I don't know how many behinds this has saved, but if this is problematic for admins I can just make it so that it lets you do it anyway. I'm not sure what the point of this babysitting was anyway.
Requested by @optimumtact.
Changelog
cl
admin: Calling a proc while another admin is calling one will no longer wait for the first to finish. You will simply just have to call it again.
/cl
