FindPatch: Fix typo in find_program call

There is no `NAME` option.  It should be `NAMES`.  The call worked
with `NAME` only due to old `find_program` signature compatibility.

After this, the `find_program` call works even with PATHS removed
(on non-Windows systems where this PATHS is not needed).

Modules/FindPatch.cmake

@@ -43,7 +43,7 @@ endif()
 
 # First search the PATH
 find_program(Patch_EXECUTABLE
-  NAME patch
+  NAMES patch
   PATHS ${_patch_path}
   DOC ${_doc}
   )