Add new files to the build.

Test: ndk/checkbuild.py
Bug: https://github.com/android-ndk/ndk/issues/216
Change-Id: I9fb05f277dfdd234b0aa1e3baf937765b5ffe5e8
diff --git a/Android.mk b/Android.mk
index 3f9bf0e..edcd5bb 100644
--- a/Android.mk
+++ b/Android.mk
@@ -32,6 +32,7 @@
     src/cxa_vector.cpp \
     src/cxa_virtual.cpp \
     src/exception.cpp \
+    src/fallback_malloc.cpp \
     src/private_typeinfo.cpp \
     src/stdexcept.cpp \
     src/typeinfo.cpp