use do() instead of require() to include configuration

When run under mod_perl, require() will read and execute the configuration
file on the first invocation only.  On every subsequent invocation, all
configuration variables will be reset to their default values.  do() reads
and executes the configuration file unconditionally.

Signed-off-by: Dennis Stosberg <dennis@stosberg.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

gitweb/gitweb.perl

@@ -152,7 +152,7 @@ sub feature_snapshot {
 our @diff_opts = ('-M'); # taken from git_commit
 
 our $GITWEB_CONFIG = $ENV{'GITWEB_CONFIG'} || "++GITWEB_CONFIG++";
-require $GITWEB_CONFIG if -e $GITWEB_CONFIG;
+do $GITWEB_CONFIG if -e $GITWEB_CONFIG;
 
 # version of the core git binary
 our $git_version = qx($GIT --version) =~ m/git version (.*)$/ ? $1 : "unknown";