perl: use the 'if' module to conditionally load File::Glob

Trying to use normal perl conditions to conditionally 'use' a perl
module didn't quite work.  Using the 'if' module to do so does work.

Reviewed-by: Andy Polyakov <appro@openssl.org>

util/process_docs.pl

diff --git a/util/process_docs.pl b/util/process_docs.pl
index cf1d326..fe8589b 100644
--- a/util/process_docs.pl
+++ b/util/process_docs.pl
@@ -13,9 +13,7 @@
 use File::Basename;
 use File::Copy;
 use File::Path;
-if ($^O ne "VMS") {
-    use File::Glob qw/glob/;
-}
+use if $^O ne "VMS", 'File::Glob' => qw/glob/;
 use Getopt::Long;
 use Pod::Usage;