The file: glib-gettext.m4 was obtained from glib2-devel (go figure!)

They are used in graphviz to avoid requiring gettext be installed.

The file ax_check_compile_flag.m4 was obtained from commit
0fbee2a29b67cc7867cfe19d473e9fb1f729f771 of
    https://git.savannah.gnu.org/git/autoconf-archive.git

The files ax_cxx_compile_stdcxx.m4 and ax_cxx_compile_stdcxx_11.m4 were obtained
from commit efa6f204a6124e882abbbc6e056c91edfdc30555 of
    https://git.savannah.gnu.org/git/autoconf-archive.git