Windows:  Create named shared memory segments under the "Local" 
namespace if the caller is unprivileged, fixing an inability of
unprivileged callers to use apr_shm_create() with named shared
memory segments under recent Windows.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1531768 13f79535-47bb-0310-9956-ffa450edef68