- Some small Perl enhancements for Do-compile: use more Perl builtins.

Build-tools/Do-compile:
   - use more Perl builtins (e.g. hostname(), basename()) instead of forking
     subprocesses

Build-tools/Do-compile

 #!/usr/bin/perl -w
 
+use File::Basename;
 use Getopt::Long;
+use Sys::Hostname;
 
 @config_options= ();
 @make_options= ();
@@ -75,7 +77,7 @@ if (@config_env > 0)
 	$opt_config_env= join(" ", @config_env);
 }
 
-chomp($host=`hostname`);
+$host= hostname();
 chomp($uname=`uname`);
 $full_host_name=$host;
 $connect_option= ($opt_tcpip ? "--host=$host" : "");
@@ -83,7 +85,7 @@ $host =~ /^([^.-]*)/;
 $host=$1 . $opt_suffix;
 $email="$opt_user\@mysql.com";
 chomp($pwd = `pwd`);
-$VER= `basename $opt_distribution`; chop $VER;
+$VER= basename($opt_distribution);
 $VER=~ /mysql.*-([1-9]\.[0-9]{1,2}\.[0-9]{1,2}.*)\.tar*/; $version=$1;
 ($major, $minor, $release) = split(/\./,$version);
 $log="$pwd/Logs/$host-$major.$minor$opt_version_suffix.log";
@@ -110,7 +112,7 @@ if (defined($gcc_version) && ! $opt_config_env)
 $new_opt_tmp=0;
 if ($opt_tmp)
 {
-  if (! -d $opt_tmp)
+  unless (-d $opt_tmp)
   {
     safe_system("mkdir $opt_tmp");
     $new_opt_tmp=1;