Windows has EACCES, not EACCESS

Once again spotted by mobmix

Also add a changes file for the fix

changes/bug2504

@@ -0,0 +1,5 @@
+  o Minor bugfixes:
+    - Fix a bug with our locking implementation on windows that couldn't
+      correctly detect when a file was already locked. Fixes bug 2504,
+      bugfix on 0.2.1.6-alpha.
+

src/common/compat.c

@@ -699,7 +699,7 @@ tor_lockfile_lock(const char *filename, int blocking, int *locked_out)
 #ifdef WIN32
   _lseek(fd, 0, SEEK_SET);
   if (_locking(fd, blocking ? _LK_LOCK : _LK_NBLCK, 1) < 0) {
-    if (errno != EACCESS && errno != EDEADLOCK)
+    if (errno != EACCES && errno != EDEADLOCK)
       log_warn(LD_FS,"Couldn't lock \"%s\": %s", filename, strerror(errno));
     else
       *locked_out = 1;