Dexopt: read min new methods/classes percent change from properties.

Bug: 172490638
Test:
1) flash locally
2) adb shell setprop name value
3) adb shell stop
4) adb shell start
5) adb shell cmd package compile -r bg-dexopt com.android.phone
Change-Id: I4049b7cecaef8a01eabf29868362065e466327b0