build: Use AC_MSG_ERROR instead of obsolete AC_ERROR

configure.ac

@@ -95,7 +95,7 @@ DPKG_CHECK_COMPAT_FUNCS([getopt getopt_long obstack_free \
                          scandir alphasort unsetenv])
 AC_CHECK_DECLS([strnlen], [[#include <string.h>]])
 AC_CHECK_FUNCS([memcpy lchown],
-               [], [AC_ERROR([missing required function])])
+               [], [AC_MSG_ERROR([missing required function])])
 AC_CHECK_FUNCS([strtoimax isascii setsid getdtablesize \
                 getprogname getexecname lutimes posix_fadvise])