Add semaphore tests, fix sem_destroy.

Bug: https://code.google.com/p/android/issues/detail?id=76088
Change-Id: I4a0561b23e90312384d40a1c804ca64ee98f4066
diff --git a/tests/Android.mk b/tests/Android.mk
index 890e203..59fe57d 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -86,6 +86,7 @@
     regex_test.cpp \
     sched_test.cpp \
     search_test.cpp \
+    semaphore_test.cpp \
     signal_test.cpp \
     stack_protector_test.cpp \
     stdatomic_test.cpp \