Log Message:
apr: update to 1.7.4.

Changes for APR 1.7.4

  *) Fix a regression where writing to a file opened with both APR_FOPEN_APPEND
     and APR_FOPEN_BUFFERED did not properly append the data on Windows.
     (This regression was introduced in APR 1.7.3)  [Evgeny Kotkov]