mail: overloaded hostname() definition causes error (#519)

* In package "mailer", hostname() is a setter method for object attribute "hostname" (L48)
* Sys::Hostname auto-imports a hostname() which causes a conflict; as a result I cannot send a mail message with 'm' command
* Prevent auto-import of Sys::Hostname symbols to resolve this

bin/mail

@@ -41,7 +41,7 @@ package
 @ISA=qw(PerlPowerTools::mailprog);
 
 use IO::Socket;
-use Sys::Hostname;   # Claims to be standard?
+use Sys::Hostname qw();
 
 %mailer::fields=(
 	  user => undef,
@@ -83,7 +83,7 @@ sub new {
 		}
 		# Find my address...
 		if (! defined $ENV{HOSTNAME}) {
-			my $hostname=hostname();
+			my $hostname = Sys::Hostname::hostname();
 			if (! $hostname) {
 				die "Unable to find a reasonable hostname.  Use \$HOSTNAME.\n";
 			}