The recent addition of `exit's prototype in confdefs.h causes

The recent addition of `exit's prototype in confdefs.h causes
AC_OUTPUT_MAKE_DEFS to include junky -D switches.
Reported by Wolfgang Mueller.
* tests/torture.at (#define header templates): Include trash in
confdefs.h.
* tests/atgeneral.at (AT_INIT): Don't expect `find' to support
-maxdepth, hence don't use -follow either.
Reported by Nicolas Joly.
* acgeneral.m4 (AC_OUTPUT_MAKE_DEFS) <confdef2opt.sed>: In the
`quote' section, `p'rint the result.
If neither `#define' pattern match, just call `d' to start a new
cycle.
Call this sed program with -n.