vmarea and heap exit flags not reset on re-init

Created by: s-kanev

This came up in the following case:

• static attach with a client (drmemtrace), which detaches with dr_app_stop_and_cleanup().
• later, from the same process, invoke raw2trace_t, which uses dr_init_standalone() to map modules and decode instructions. Mapping modules then fails because update_dynamo_areas_on_release() doesn't remove VM areas thinking it's exiting, because both vm_areas_exited and heap_exiting are still set.

The fix is simple, don't statically initialize them, but use the proper _init() functions.