`AC_PREREQ'.
* tests/tools.m4: Globally, don't use `../' to invoke the tested
tools, since the PATH is properly set, and in most cases it
obfuscates the test code.
(autoupdating AC_PREREQ): New tests.
are properly templated, autoheader traces
AC_DEFINE/AC_DEFINE_UNQUOTED. Only literals can be traced, and
actually tracing non literals produces invalid autoheader input.
Hence, provide a means to trace calls to
AC_DEFINE/AC_DEFINE_UNQUOTED with literals.
* acgeneral.m4 (AC_DEFINE_TRACE, AC_DEFINE_TRACE_LITERAL): New
macros.
(AC_DEFINE, AC_DEFINE_UNQUOTED): Use AC_DEFINE_TRACE.
* autoheader.sh: Trace AC_DEFINE_TRACE_LITERAL, not
AC_DEFINE/AC_DEFINE_UNQUOTED.
