Merge branch 'jc/test-prereq' into maint

* jc/test-prereq:
  t3910: use the UTF8_NFD_TO_NFC test prereq
  test-lib: provide UTF8 behaviour as a prerequisite
  t0050: use the SYMLINKS test prereq
  t0050: use the CASE_INSENSITIVE_FS test prereq
  test-lib: provide case insensitivity as a prerequisite
  test: allow prerequisite to be evaluated lazily
  test: rename $satisfied to $satisfied_prereq

diff --cc t/test-lib-functions.sh
Simple merge