* rdi-share/Makefile.am, rdi-share/aclocal.m4,
rdi-share/configure: New files.
* rdi-share/configure.in: Rewritten to be an autoconf input file.
* rdi-share/Makefile.in, rdi-share/configure: Generated by
automake/autoconf.
* rdi-share/dbg_hif.h, etherdrv.c, hostchan.c: Use autoconf tests
to check environment.
automake/autoconfiscate rdi-share. We don't use the checks that autoconf
provides too much for now, but it'll be easier to use them if any problems
crop up in the future. (rdi-share/ is foreign code and it probably isn't
worth spending any more time than necessary messing with it.)