Regtest/stability changes for drd (Bart Van Assche)

- Fix helgrind/tests/tc18_semabuse.c on glibc 2.7 (RedHat 8).

- Fixed a glibc 2.7 specific assertion failure in exp-drd, namely one
  that was triggered when sem_post()'s return value is not zero.

- exp-drd/test/matinv.c compiles now also on RedHat 7.3.

Note: more work will be required to get exp-drd working correctly on
RedHat 7.3.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@7354 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/exp-drd/drd_clientreq.c b/exp-drd/drd_clientreq.c
index ac4b045..a3d5287 100644
--- a/exp-drd/drd_clientreq.c
+++ b/exp-drd/drd_clientreq.c
@@ -197,7 +197,7 @@
       break;
 
    case VG_USERREQ__POST_SEM_POST:
-      drd_semaphore_post_post(thread_get_running_tid(), arg[1], arg[2]);
+      drd_semaphore_post_post(thread_get_running_tid(), arg[1], arg[2], arg[3]);
       break;
 
    case VG_USERREQ__BARRIER_INIT: