Merge branch 'maint' * maint: maint: targets and recipes to simplify testing on real-world packages build: preparatory refactoring build: tiny reduction in code duplication make flags analysis: handle more options with args make flags analysis: use simpler variable names make flags analysis: whitespace changes make flags analysis: embed in a subshell make flags analysis: be more robust make flags analysis: cater to GNU make 3.83 (still unreleased as of now) tests: expose weaknesses in make flags analysis tests: improve debugging output in checks on make flags analysis make flags analysis: refactor, to reduce code duplication tests: avoid one tricky use of "make -e" cosmetics: remove few trailing whitespace occurrences typofix: in NEWS (extra whitespace) tests: avoid a spurious error with Solaris make subdirs: don't return false positives for the '-k' option's presence header-vars: recognize more make flags ('-k' in particular) header-vars: simplify how make flags are determined tests: remove dead code from t/make-dryrun.tap header-vars: new variable $(am__running_with_option) tests: expose bug#12554 (false positives for presence of '-k' make option)