Add a runtime flag to use JIT Zygote image.

Currently, the platform is passing non-existing boot image locations
with profile specifications via `-Ximage` to tell the runtime to use
JIT Zygote image. This is not flexible. This new `-Xusejitzygoteimage`
flag allows the platform to achieve the same thing without explicitly
specifying the locations.

This is so far a no-op change as the behavior of the new flag mirrors
the current behavior of the platform.

Bug: 203492478
Test: manual -
  1. Build a system image and flash it to a device.
  2. adb shell setprop dalvik.vm.extra-opts '-verbose:image'
  3. adb shell setprop dalvik.vm.profilebootclasspath true
  4. adb shell setprop ctl.restart zygote
  5. See the boot image extension being compiled in memory
     (http://gpaste/4688561208033280).
Change-Id: I3267b5e84136a13913722fae5a34dbea9c2bf960
2 files changed