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/libc/Android.mk b/libc/Android.mk
index e58d4fb..edf834b 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -358,7 +358,7 @@
 #
 libc_static_common_src_files := \
         bionic/__errno.c \
-        bionic/sysconf.c \
+        bionic/sysconf.cpp \
 
 # Architecture specific source files go here
 # =========================================================