style: [patch 3/22] reduce include dependencies in some headers

Used cppclean to help identify useless includes and removed them. This
involved erroneously included headers, but also cases where forward
declarations could have been used rather than a full include.

src/sim/vptr.hh

@@ -31,8 +31,6 @@
 #ifndef __ARCH_ALPHA_VPTR_HH__
 #define __ARCH_ALPHA_VPTR_HH__
 
-#include "arch/isa_traits.hh"
-#include "arch/vtophys.hh"
 #include "mem/fs_translating_port_proxy.hh"
 
 class ThreadContext;