provide an RL variant that prints an extra argument

use __dead

cast and mask is overkill.

cast to destination type.

PR/47826: Garrett Cooper: Add <sys/types.h>. Really I am tempted to remove
this file instead.

Add __printflike attribution to use vprintf and friends with an argument
as format string.

Use proper format strings.

Add RZ(), which is like RL() except that it checks against 0 and
uses the return value as the error number instead of errno.

Need stdlib.h.

Thanks to Sverre Froyen for pointing this out.

Make random garbage more widely available.

use normal include-protection

Add atf_tc_fail_errno(), which appends strerror(errno) to the
message string. Adding it to h_macros suggested by jmmv

Add helper macros for tests.