Re: build from tarball uses bison

[Bruno Haible]

> > bison -d -t --report=state --output pk-map-tab.c \
> >           ../../poke/pk-map-tab.y
> >
> > While the GCS allow this (see
> > <https://www.gnu.org/prep/standards/html_node/Utilities-in-Makefiles.html>),
> > it is a best practice to avoid bison as a build prerequisite, by packaging
> > the generated files in the tarball. See
> > <https://www.gnu.org/prep/standards/html_node/Makefile-Basics.html>
> >
> > The attached patch to poke/Makefile.am fixes this.
> >
> > The libpoke/ subdirectory has a related problem: It distributes the
> > pkl-tab.h and pkl-tab.c files (good!), but erases them during "make clean".
> > After "make clean", "make" then needs bison here as well:
> >
> > bison -d -t --report=state --output pkl-tab.c \
> >           ./pkl-tab.y
> >
> > Also fixed in the patch.
> 
> OK for master.
> Thanks!

Pushed.