Increase performance of the squidclamav redirector.

To boost up the performance, now we trust the proxy cache.

I add some changes to the proxy.cgi to configure the proxy and the
squidclamav in the right way.

I also add a hook that allows us to generate a new configuration
if the cgi script will be launched from the shell.

Fixes #10367.

config/cfgroot/general-functions.pl

@@ -1008,4 +1008,27 @@ sub MakeUserAgent() {
 	return $user_agent;
 }
 
+# Function to read a file with UTF-8 charset.
+sub read_file_utf8 ($) {
+	my ($file) = @_;
+
+	open my $in, '<:encoding(UTF-8)', $file or die "Could not open '$file' for reading $!";
+	local $/ = undef;
+	my $all = <$in>;
+	close $in;
+
+	return $all;    
+}
+
+# Function to write a file with UTF-8 charset.
+sub write_file_utf8 ($) {
+	my ($file, $content) = @_;
+
+	open my $out, '>:encoding(UTF-8)', $file or die "Could not open '$file' for writing $!";;           
+	print $out $content;
+	close $out;
+
+	return; 
+}
+
 1;