Update JIT Zygote image option.

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: I69c11e3e41b9ab142b427ee054c2a6275ff089de