maint: chown.c: remove a comment
tests: fix link failure on cygwin
build: fix link failure on cygwin
tests: avoid test failures when PATH contains an unsearchable directory
tests: do not fail on read-only root file system
maint: cfg.mk: remove factored-out ftp host/dir definitions
maint: correct comments in test scripts
maint: don't list "warnings" module explicitly
build: update gnulib submodule to latest
maint: move xfreopen module to gnulib