generates too many bug reports.
* lib/autoconf/general.m4 (_AC_RUN_IFELSE): Pass the right exit
status when executing the ACTION-IF-FALSE.
* tests/base.at (AC_TRY_*): Rename as...
(AC_TRY_COMMAND): this.
(AC_RUN_IFELSE): New.
* tests/compile.at (Extensions, C keywords)
(AC_PROG_CPP requires AC_PROG_CC, GNU Fortran 77)
(Broken/missing compilers, AC_PROG_CPP with warnings)
(AC_PROG_CPP without warnings, AC_PROG_CPP via CC): Move to...
* tests/c.at (Extensions, C keywords)
(Broken/missing compilers, AC_PROG_CPP with warnings)
(AC_PROG_CPP without warnings, AC_PROG_CPP via CC)
(AC_PROG_CPP requires AC_PROG_CC): here and...
* tests/fortran.at (GNU Fortran 77): there.
* doc/autoconf.texi (autoconf Invocation): Fix the example:
AC_TRY_RUN is about compilation, not shell commands.
(Test Programs): AC_TRY_RUN works as used to be advertised.
