Fixes build.

This change somehow went missing from the vfork change.

Change-Id: I807a2072080eac20601c694e85ba5723220289d8
(cherry picked from commit 9eae8405e8f70e489f2fe350a0212ab8114cbd17)
diff --git a/libc/Android.mk b/libc/Android.mk
index 46c9676..2007965 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -226,7 +226,6 @@
     bionic/unlink.cpp \
     bionic/utimes.cpp \
     bionic/vdso.cpp \
-    bionic/vfork.cpp \
     bionic/wait.cpp \
     bionic/wchar.cpp \
     bionic/wctype.cpp \