I'm not 100% certain because i've never done this before. From what i saw it looks like you can either put that into your php.ini, or into a .htaccess.

AddType application/x-httpd-php .php .htm .html
//Tells the server to treat html and htm files as php files.

< FilesMatch "\.(php?)$" >
php_value auto_prepend_file "/the/path/that/leads/to/count.php "
</FilesMatch >
//Adds your adpage (e.g. /the/path/that/leads/to/count.php) to beginning of all php files.

Might not have everything perfect, but i think that's close.

<center><script type="text/javascript"><!--
google_ad_client = "pub-0154875139772011";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_ad_type = "text_image";
google_ad_channel ="1290573937";
//--></script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script></center>
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