e2fsck missing from emulator

The emulator file system was recently switched to ext4 however, e2fsck was not
added to the emulator build.

Change-Id: I94621c148fa40d6042b5c86a26815d867a417a6c
See: https://code.google.com/p/android/issues/detail?id=64144
diff --git a/target/product/emulator.mk b/target/product/emulator.mk
index 439e6c7..6812c22 100644
--- a/target/product/emulator.mk
+++ b/target/product/emulator.mk
@@ -53,7 +53,8 @@
     camera.goldfish.jpeg \
     lights.goldfish \
     gps.goldfish \
-    sensors.goldfish
+    sensors.goldfish \
+    e2fsck
 
 
 PRODUCT_COPY_FILES += \