Make sure we have a mkfifo symbol.

Bug: https://code.google.com/p/android/issues/detail?id=58888
Change-Id: Ic0a883a5f30beb82cb7be3c4e81b6d693d5fbb4d
diff --git a/libc/Android.mk b/libc/Android.mk
index 72b6dc8..33f2362 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -224,6 +224,7 @@
     bionic/libc_init_common.cpp \
     bionic/libc_logging.cpp \
     bionic/libgen.cpp \
+    bionic/mkfifo.cpp \
     bionic/pthread_attr.cpp \
     bionic/pthread_detach.cpp \
     bionic/pthread_equal.cpp \