CFLAGS="-Wall -Wextra -Wconversion $CFLAGS"
fi
-AC_CHECK_HEADERS([error.h])
+AC_CHECK_HEADERS([err.h error.h])
AC_CHECK_HEADERS([fcntl.h],
[],[AC_MSG_ERROR([header is required])])
AC_CHECK_FUNCS([memmove setenv],
[],[AC_MSG_ERROR([function is required])])
AC_CHECK_FUNCS([execvpe])
+dnl These are not in POSIX.
+AC_CHECK_FUNCS([fwrite_unlocked fputs_unlocked fputc_unlocked])
+dnl Internal functions in libc implementations which must be hooked.
+AC_CHECK_FUNCS([__overflow __swbuf])
dnl Thanks to gperftools' configure.ac (https://code.google.com/p/gperftools).
AC_MSG_CHECKING([for __builtin_expect])
fi])
dnl Used in tests/Makefile.am to build the test only if function is available.
+AM_CONDITIONAL([HAVE_ERR_H],[test "x$ac_cv_header_err_h" = xyes])
AM_CONDITIONAL([HAVE_ERROR_H],[test "x$ac_cv_header_error_h" = xyes])
AM_CONDITIONAL([HAVE_VFORK],[test "x$ac_cv_func_vfork_works" = xyes])