DURATION fails to accurately work for requests that take more than one second

[aweits]

apr_time_usec is apparently defined as follows:

define apr_time_usec ( time) ((time) % APR_USEC_PER_SEC)

Which leads re_variables.c:1740 to not behave as expected when duration exceeds one second.

[victorhora]

Fixed as of: 3044ad0