add tag for vvar and vdso regions, this will stop MADV_DONTNEED

[sv641]

vvar and vdso are always needed.

[paulpopelka]

This change is reverting the following commit:

commit e795afa
Author: paulpopelka paulp@kontain.app
Date: Thu Mar 2 12:07:39 2023 -0800

Fix km to allow gdb to use the symbols in the vdso pages (#1743)

Don't assign a filename to the vvar and vdso regions in the km memory busy map.
km was assigning the non-filenames [vvar] and [vdso] to the vdso regions
which apparently prevented gdb from checking to see if they were the
vdso area.

A quick way to test is run gdb on a payload coredump and then
run the "disassem gettimeofday" command.
You will see symbols like __vdso_gettimeofday in the output which tells
you gdb was able to access the symbols stored in the vdso pages.

Is there some way to allow both "needs" to be met?

[sv641]

It is a longer fix. I will do that.