The current include_path setting is shown as part of that error message in case you were specifying a relative path/file to be required, in which case the include_path would have been searched to find the location of the file. Since you are specifying an absolute filesystem path/file, the include_path has no relevance and you can ignore it being in the error message. The include_path setting containing an entry for the pear extension, does not mean that pear is need or installed, just that the include_path contains a default entry for it.
You should have also gotten a WARNING message prior to that fatal error, telling you why the file could not be required. If you didn't, it means that php's error_reporting setting is not set to E_ALL. You need to find where the error_reporting setting is set at on your system and change it to be E_ALL. If it is set in a php.ini file, you will need to restart the web server to get any change made to the php.ini to take effect. After you have changed the settings, use a phpinfo(); statement in a .php script to confirm that the setting actually got changed.