Merge branch 'minor'

Merge branch 'minor'

* minor:
  cleanup: refactor code to initialize DIST_COMMON
  dist: ordering of files in DIST_COMMON is deterministic now
  tests: refactor some tests on DIST_COMMON
  maint: make output of 'gen-testsuite-part' deterministic
  When computing lispdir, don't load emacs site wide init file.
  PATH: quote $(PATH_SEPARATOR) as well
  Improve detection of GNU make, avoiding "Arg list too long" errors.