Merge r1529521 and r1529668 from trunk:

Don't include windows.h when building for Cygwin.

PR: 55586
Submitted by: Carlo Bramini <carlo.bramix libero.it>

Cygwin: Don't define unused symbol "CYGWIN".  (__CYGWIN__ is used instead.)

PR: 51016
Submitted by: Carlo Bramini <carlo.bramix libero.it>


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.5.x@1529671 13f79535-47bb-0310-9956-ffa450edef68