Applying a patch not generated by Git in a subdirectory used to
check the whitespace breakage using the attributes for incorrect
paths. Also whitespace checks were performed even for paths
excluded via "git apply --exclude=<path>" mechanism.

* jc/apply-ws-prefix:
  apply: omit ws check for excluded paths
  apply: hoist use_patch() helper for path exclusion up
  apply: use the right attribute for paths in non-Git patches