(nanosleep):

Don't use SA_INTERRUPT to decide whether to call sigaction, as
POSIX.1 doesn't require SA_INTERRUPT and some systems
(e.g. Solaris 7) don't define it.  Use SA_NOCLDSTOP instead;
it's been part of POSIX.1 since day 1 (in 1988).

lib/nanosleep.c

@@ -61,7 +61,7 @@ int
 nanosleep (const struct timespec *requested_delay,
 	   struct timespec *remaining_delay)
 {
-#ifdef SA_INTERRUPT
+#ifdef SA_NOCLDSTOP
   struct sigaction oldact, newact;
 #endif
 
@@ -70,7 +70,7 @@ nanosleep (const struct timespec *requested_delay,
   /* set up sig handler */
   if (first_call)
     {
-#ifdef SA_INTERRUPT
+#ifdef SA_NOCLDSTOP
       newact.sa_handler = sighandler;
       sigemptyset (&newact.sa_mask);
       newact.sa_flags = 0;