Use PACKAGE_NAME instead of GNU_PACKAGE.

Use PACKAGE_NAME instead of GNU_PACKAGE.
* src/Makefile.am (.sh, uninstall-local): Adjust all users of
hand-rolled GNU_PACKAGE to instead use autoconf-provided
PACKAGE_NAME.
* src/basename.c (main): Likewise.
* src/chroot.c (main): Likewise.
* src/dirname.c (main): Likewise.
* src/echo.c (main): Likewise.
* src/expr.c (main): Likewise.
* src/factor.c (main): Likewise.
* src/groups.sh (version): Likewise.  Also, reflect change in
--version output due to GPLv3.
* src/hostid.c (main): Likewise.
* src/hostname.c (main): Likewise.
* src/link.c (main): Likewise.
* src/logname.c (main): Likewise.
* src/nice.c (main): Likewise.
* src/nohup.c (main): Likewise.
* src/printenv.c (main): Likewise.
* src/printf.c (main): Likewise.
* src/pwd.c (main): Likewise.
* src/setuidgid.c (main): Likewise.
* src/sleep.c (main): Likewise.
* src/system.h (case_GETOPT_VERSION_CHAR): Likewise.
* src/test.c (main): Likewise.
* src/true.c (main): Likewise.
* src/unlink.c (main): Likewise.
* src/uptime.c (main): Likewise.
* src/users.c (main): Likewise.
* src/whoami.c (main): Likewise.
* src/yes.c (main): Likewise.
* configure.ac (AC_CHECK_DECLS): No need to check strtoimax,
strtoumax, since gnulib does this.