scheme48 fails to cross build from source, because it uses AC_TRY_RUN a
lot and it doesn't work during cross compilation. In many cases, the use
is not necessary. For instance determining the size of a pointer can be
done with AC_CHECK_SIZEOF. In other cases, the program being run simply
is int main() { return 0; } and that doesn't provide any benefit over
AC_LINK_IFELSE. I am attaching a patch that reduces some amount of
AC_TRY_RUN and thus brings scheme48 quite a bit close to cross building.
Many of the remaining checks actually do need to run something. Going
further probably requires exporting cached check results. In this bug
report, I want to focus on the low hanging fruit though. Do you find the
proposed changes acceptable?

Helmut