Use a simpler method to build a glob than splitpath and catpath

It turns out that the combination splitpath() could return an empty
string for the directory part.  This doesn't play well with catdir().
Reviewed-by: NRich Salz <rsalz@openssl.org>

Configure

@@ -10,7 +10,7 @@
 require 5.000;
 use strict;
 use File::Basename;
-use File::Spec::Functions qw/:DEFAULT abs2rel rel2abs catpath splitpath/;
+use File::Spec::Functions qw/:DEFAULT abs2rel rel2abs/;
 use File::Path qw/make_path/;
 use Cwd qw/:DEFAULT realpath/;
 
@@ -175,8 +175,7 @@ die "erroneous version information in opensslv.h: ",
 
 # Collect target configurations
 
-my ($vol, $dir, $dummy) = splitpath($0);
-my $pattern = catpath($vol, catdir($dir, "Configurations"), "*.conf");
+my $pattern = catfile(dirname($0), "Configurations", "*.conf");
 foreach (sort glob($pattern) ) {
     &read_config($_);
 }