Fix errors with CacheLock on Windows:

cache_util.c(757): (OS 80)The file exists.  : [client 127.0.0.1:63889] 
AH00784: Attempt to obtain a cache lock for stale cached URL failed, 
revalidating entry anyway: 


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1588704 13f79535-47bb-0310-9956-ffa450edef68