Quicker partial collection by using card marking.

Add calls to the card marking from the write barrier routines, so that
a write to an Object marks the appropriate card. Add code in the GC to
use and rebuild the cards at a partial GC, clearing cards in the
Zygote heap which do not in fact contain references to the application
heap.

Change-Id: Ie6f29fd096e029f48085715b282b6db8a7122555
diff --git a/vm/Dvm.mk b/vm/Dvm.mk
index 3214e31..8626375 100644
--- a/vm/Dvm.mk
+++ b/vm/Dvm.mk
@@ -130,6 +130,7 @@
 	UtfString.c \
 	alloc/clz.c.arm \
 	alloc/Alloc.c \
+	alloc/CardTable.c \
 	alloc/HeapBitmap.c.arm \
 	alloc/HeapDebug.c \
 	alloc/HeapTable.c \