[Local GC] Undefined symbol when building standalone: g_SystemInfo

[swgillespie]

  "_g_SystemInfo", referenced from:
      SVR::WaitLongerNoInstru(int) in gcsvr.cpp.o
      SVR::get_valid_segment_size(int) in gcsvr.cpp.o
      SVR::gc_heap::grow_brick_card_tables(unsigned char*, unsigned char*, unsigned long, SVR::heap_segment*, SVR::gc_heap*, int) in gcsvr.cpp.o
      SVR::gc_heap::get_large_segment(unsigned long, int*) in gcsvr.cpp.o
      SVR::gc_heap::gc_thread_function() in gcsvr.cpp.o
      SVR::gc_heap::make_card_table(unsigned char*, unsigned char*) in gcsvr.cpp.o
      SVR::gc_heap::enter_gc_done_event_lock() in gcsvr.cpp.o
      ...

These should be using GCToOSInterface instead.