Fix BLI_rename returning success on failure for WIN32

When the `from` file didn't exist, BLI_rename returned success,
the in-line doc-string was incorrect - remove in favor of the header's
doc-string. This error existed since the initial revision.
Note that this was fixed [0] for other systems.

[0]: 622019a085

source/blender/blenlib/intern/fileops.c

@@ -691,11 +691,10 @@ int BLI_create_symlink(const char *file, const char *to)
 }
 #  endif
 
-/** \return true on success (i.e. given path now exists on FS), false otherwise. */
 int BLI_rename(const char *from, const char *to)
 {
   if (!BLI_exists(from)) {
-    return 0;
+    return 1;
   }
 
   /* Make sure `from` & `to` are different (case insensitive) before removing. */