minidump: De-duplicate is_dumpable()

[mhorne]

Summary

The function is identical in each minidump implementation, and it is
small, so move it to the vm_dumpset.h header. The only slight exception
is powerpc where the function is public, for use in moea64_scan_pmap().

Test Plan

Will tinderbox.

[imp]

Looks identical modulo int->bool changes, which don't matter.

[markj]

This is a good cleanup. I don't really like the header pollution. We are already assuming that consumers have included vm_page.h (to check m->flags & PG_NODUMP), so why not vm_phys.h as well? Alternately we could have the implementation live in vm_phys.c and call it vm_phys_is_dumpable() or so.

[mhorne]

In D31884#719396, @markj wrote:

This is a good cleanup. I don't really like the header pollution. We are already assuming that consumers have included vm_page.h (to check m->flags & PG_NODUMP), so why not vm_phys.h as well? Alternately we could have the implementation live in vm_phys.c and call it vm_phys_is_dumpable() or so.

Sure, I will drop the include from this header. I considered vm_phys.c as well, but currently nothing in that file touches dump_avail, so this seems the more natural place.

[mhorne]

Drop include of vm_phys.h from vm_dumpset.h. Include it where it is needed instead.

[kib]

I am fine with this as is, but I think my minor preference is to have the function moved to vm_phys.c.

[markj]

I suspect vm_dumpset.h should be wrapped in #ifdef _KERNEL as well, just in case some other header starts including it.

[mhorne]

Move function to vm_phys.c, rename it to vm_phys_is_dumpable().