static-build: don't use cat to apply multiple patches

The problem is if cat fails, because a patch file doesn't exist
PATH_COMMAND written like this won't detect it, because the last
command (patch) will complete successfully (apply existing patches
found by cat):

  cat XXX.patch YYY.patch | patch -p1

The proper way is to use PATCH_COMMAND continuation:

  PATCH_COMMAND patch -p1 -i XXX.patch
  COMMAND       patch -p1 -i YYY.patch

NO_DOC=build
NO_TEST=build
NO_CHANGELOG=build