Add copyright notice, as nontrivial m4 files are supposed to have them these days. (AC_FUNC_STRERROR_R): Always do char* test, so that it gets cached. Merge changes from latest Autoconf CVS. Rename ac_cv_func_strerror_r_works to ac_cv_func_strerror_r_char_p, and rename HAVE_WORKING_STRERROR_R to STRERROR_R_CHAR_P, since POSIX decided to standardize on the int flavor of strerror_r.