Add missing POSIX 2024 tests.

I'd already done some (such as qsort_r()), but hadn't systematically gone through the additions.

Change-Id: Ia8e848f2554c0096b6e399e13b88bee03cb9eb84
diff --git a/tests/headers/posix/poll_h.c b/tests/headers/posix/poll_h.c
index 4fce5e5..505ba46 100644
--- a/tests/headers/posix/poll_h.c
+++ b/tests/headers/posix/poll_h.c
@@ -36,6 +36,11 @@
   STRUCT_MEMBER(struct pollfd, short, events);
   STRUCT_MEMBER(struct pollfd, short, revents);
 
+#if !defined(__GLIBC__)  // Our glibc is too old.
+  TYPE(sigset_t);
+  TYPE(struct timespec);
+#endif
+
   TYPE(nfds_t);
 
   MACRO(POLLIN);
@@ -50,4 +55,7 @@
   MACRO(POLLNVAL);
 
   FUNCTION(poll, int (*f)(struct pollfd[], nfds_t, int));
+#if !defined(__GLIBC__)  // Our glibc is too old.
+  FUNCTION(ppoll, int (*f)(struct pollfd[], nfds_t, const struct timespec*, const sigset_t*));
+#endif
 }