Merge r1531768 and r1533979 from trunk:

r1531768:

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.

r1533979:

Add apr_shm_create_ex() and apr_shm_attach_ex(), which
provide the ability to select the Global or Local
namespace on Windows.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/branches/1.5.x@1534011 13f79535-47bb-0310-9956-ffa450edef68