tests: readdir-mountpoint-inode avoid false-positive w/virtualbox
id: handle systems without getgroups support
tests: fix a bug in sanitize_path_ that inhibited verbose output
sort: fix link failure on Solaris
rm: fix empty-name bug introduced with conversion to use fts
bootstrap: fix handling of various perl --version formats
bootstrap: update from gnulib, for perl-5.11.x support
build: update gnulib submodule to latest
maint: chown.c: remove a comment
tests: fix link failure on cygwin