Standard way to use m4sugar

[Peng Yu]

Hi,

I see that m4sugar has been included in autoconf and bison. It sounds
like it could be made into a stand alone package. Unfortunately, it is
not.

https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Programming-in-M4sugar.html#Programming-in-M4sugar

They are installed in something like the following via homebrew.
However, the location is not standard. I could manually set M4PATH or
use -I manually. But it could break when there is an update in
homebrew and I will always need to monitor the m4sugar path which is
inconvenient.

/usr/local/Cellar/bison/3.0.5/share/bison/m4sugar/
/usr/local/Cellar/autoconf/2.69/share/autoconf/m4sugar/
/usr/local/Cellar/bison/3.0.4_1/share/bison/m4sugar/

Could anybody show me the best way to let m4 use m4sugar? Thanks.

--
Regards,
Peng