* branch-1.13.2:
docs: issues with configure substitutions in TESTS
tests: avoid possible autotools caching issues (automake bug#13832)
docs: add myself and Ralf Wildenhues as authors
authors: add myself
dry-run: don't get confused by '-I' option
tests: avoid a spurious failure with the Korn Shell
dry-run: with GNU make, prefer $(MFLAGS) over $(MAKEFLAGS)
header vars: can determine whether we are running under GNU make
NEWS: improve wording for automake bug#13514 fix
NEWS: document fix for automake bug#13514