Fix determination of Perl interpreter: A perl or perl5
_directory_ in $PATH was also accepted as the interpreter.

Configure

diff --git a/Configure b/Configure
index 4c104dd..6271742 100755
--- a/Configure
+++ b/Configure
@@ -753,7 +753,7 @@
 	my $path;
 	foreach $path (split /:/, $ENV{PATH})
 		{
-		if (-x "$path/$name")
+		if (-f "$path/$name" and -x _)
 			{
 			return "$path/$name" unless ($name eq "perl" and
 			 system("$path/$name -e " . '\'exit($]<5.0);\''));