Multiple -trusted/-untrusted/-CRLfile options in verify

It is sometimes useful (especially in automated tests) to supply
multiple trusted or untrusted certificates via separate files rather
than have to prepare a single file containing them all.

To that end, change verify(1) to accept these options zero or more
times.  Also automatically set -no-CAfile and -no-CApath when
-trusted is specified.

Improve verify(1) documentation, which could still use some work.

Reviewed-by: Richard Levitte <levitte@openssl.org>

test/recipes/25-test_verify.t

@@ -8,10 +8,6 @@ use OpenSSL::Test qw/:DEFAULT top_dir top_file/;
 
 setup("test_verify");
 
-# Note for now, at most one trusted and one untrusted PEM file can be
-# specified.  The verify(1) option parser does not accumulate content
-# from multiple trusted or untrusted files.
-#
 sub verify {
     my ($cert, $vname, $trusted, $untrusted, @opts) = @_;
     my @args = qw(openssl verify -verify_name);