[Msan] Disable the ppoll unit test on FreeBSD

[eugenis]

LGTM

lib/msan/tests/msan_test.cc

TEST(MemorySanitizer, poll) {
   ASSERT_EQ(1, res);
   EXPECT_NOT_POISONED(fds[0].revents);
   EXPECT_NOT_POISONED(fds[1].revents);
 
   close(pipefd[0]);
   close(pipefd[1]);
 }
 
+// There is no ppoll() on FreeBSD.
+#if !defined (__FreeBSD__)
 TEST(MemorySanitizer, ppoll) {
   int* pipefd = new int[2];
   int res = pipe(pipefd);
   ASSERT_EQ(0, res);
 
   char data = 42;
   res = write(pipefd[1], &data, 1);
   ASSERT_EQ(1, res);
 
   pollfd fds[2];
   fds[0].fd = pipefd[0];
   fds[0].events = POLLIN;
   fds[1].fd = pipefd[1];
   fds[1].events = POLLIN;
   sigset_t ss;
   sigemptyset(&ss);
   res = ppoll(fds, 2, NULL, &ss);
   ASSERT_EQ(1, res);
   EXPECT_NOT_POISONED(fds[0].revents);
   EXPECT_NOT_POISONED(fds[1].revents);
 
   close(pipefd[0]);
   close(pipefd[1]);
 }
+#endif
 
 TEST(MemorySanitizer, poll_positive) {
   int* pipefd = new int[2];
   int res = pipe(pipefd);
   ASSERT_EQ(0, res);
 
   pollfd fds[2];
   fds[0].fd = pipefd[0];