build/phone-xhdpi-1024-dalvik-heap.mk Revert AOSP heapgrowthlimit change...

... from 64 to 96

This reverts part of AOSP change at

https://android.googlesource.com/platform/frameworks/native/+/c84e9844d621223d14178be521

Possible performance issues have arisen because of it. Discussion at

http://code.google.com/p/android/issues/detail?id=40961

Patch Set 2: Clean up commit message

Change-Id: Id7e3324607f92553a98e4d47da58a322e4fba657