Pull up following revision(s) (requested by spz in ticket #344):
external/bsd/nvi/usr.bin/recover/virecover: 1.2-1.3
external/bsd/nvi/dist/common/recover.c: 1.6-1.9
be more careful about opening recovery files... in particular deal with
people trying to get 'vi -r' stuck using named pipes, symlink attacks,
and coercing others opening recovery files they did not create.
- don't use command substitution to glob a pattern into a list of filenames;
  it is less efficient than doing it directly and does not handle whitespace
  in filenames properly.
- change test to [
- quote variables
Put back the tests for "no files matched" (in a different way than they
were written previously - but that's just style.)  This is not csh...
Use the correct test operator to test for an empty file (rather than
testing for an empty file name...)
Write test ('[') commands in a way that is defined to work, rather than
just happens to - we can afford the (negligible) performance hit here.
Deal safely with recovery mail files.
oops, accidendally committed an earlier non-working version; fixed.
Don't use popenve() for portability; forking an extra shell here is not an
issue.

(snj)