Only run the test programs that call sem_init() on operating systems that have implemented this function.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@10564 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/drd/tests/sem_as_mutex.vgtest b/drd/tests/sem_as_mutex.vgtest
index 27f63e8..dc059a0 100644
--- a/drd/tests/sem_as_mutex.vgtest
+++ b/drd/tests/sem_as_mutex.vgtest
@@ -1,3 +1,3 @@
-prereq: ./supported_libpthread
+prereq: ./supported_libpthread && ./supported_sem_init
 vgopts: --check-stack-var=yes --read-var-info=yes
 prog: sem_as_mutex