Reduce CPU consumption in conv_10 function, used to format "%d" by apr_*printf

Reduce CPU consumption in conv_10 function, used to format "%d" by apr_*printf

This includes two changes to APR:
  * new functions apr_itoa, apr_ltoa, and apr_off_t_toa
    that provide itoa-type functionality based on pools
  * Inline code in inet_ntop4 to replace sprintf for converting
    binary IP addresses into dotted-decimal format

and two changes to Apache:
  * use the apr_itoa functions in setting the content length,
    in place of apr_psprintf
  * use the apr_itoa functions to replace frequent uses of
    'sprintf("%d",...)' in mod_log_config.

Submitted by: Brian Pane
Reviewed by:  Dean Gaudet, Greg Ames

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89686 13f79535-47bb-0310-9956-ffa450edef68