put NO_LOCAL_PATCHES tests in the functions we use them

rather than inside the scripts where they are duplicated.
Note that importing into cvs is documented in bin/import_perl
Tell patch we know what are patches should do

Once they're GOOD, we don't want to hear about it.

Depending on order, sometimes the patches think they are already applied
for unknown reasons.
Build perl with a read-only source tree

So we catch problems where they write to it before it goes in.
Fix perl's Configure writing to the source dir instead of obj

Because it shouldn't do that.