init: disable destructors on global and static variables

This is generally a good practice because the destructor order is
undefined + deallocating stuff right before exit is a waste.

It also saves a surprising amount of code size. When checked with the
following command, the microdroid variant's binary size goes from
1,510,044 to 1,068,913 (-30%).

size -A out/soong/.intermediates/system/core/init/init_second_stage.microdroid/android_arm64_armv8-2a_cortex-a55/init

Test: flash and boot
Flag: EXEMPT ...
Change-Id: Ib9d623f0b0b462962476c9611c366cf6c76cd9f7