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
Merge "e2fsck missing from emulator"
Merge branch 'master' of https://android.googlesource.com/platform/build into HEAD