Define _POSIX_MONOTONIC_CLOCK and implement sysconf(_SC_MONOTONIC_CLOCK).

Bug: http://code.google.com/p/android/issues/detail?id=39680
Change-Id: I11cf10a66f9d305868a725f04f581099fb88bbfc
diff --git a/tests/Android.mk b/tests/Android.mk
index 7153383..083bb70 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -65,6 +65,7 @@
     stdlib_test.cpp \
     string_test.cpp \
     stubs_test.cpp \
+    unistd_test.cpp \
 
 test_dynamic_ldflags = -Wl,--export-dynamic -Wl,-u,DlSymTestFunction
 test_dynamic_src_files = \