* fix-part-pr13832:
tests: avoid possible autotools caching issues (automake bug#13832)
* fix-pr13760:
dry-run: don't get confused by '-I' option
dry-run: with GNU make, prefer $(MFLAGS) over $(MAKEFLAGS)
header vars: can determine whether we are running under GNU make
* fix-doc-pr14019:
docs: issues with configure substitutions in TESTS
* news-wording-improve:
NEWS: improve wording for automake bug#13514 fix