cpu: remove O3 dependency of CheckerCPU

Currently, compiling CheckerCPU uses the dyn_inst.hh header from
O3CPU. However, including this header is not required and it
causes gem5 failed to build when O3CPU is not part of CPU_MODELS.

This change also involves moving the the dependency on
src/cpu/o3/dyn_inst.hh to src/cpu/o3/cpu.cc and src/cpu/lsq_unit.cc,
which previously includes src/cpu/o3/dyn_inst.hh implicitly through
src/cpu/checker/cpu.hh.

JIRA: https://gem5.atlassian.net/browse/GEM5-1025

Change-Id: I7664cd4b9591bf0a4635338fff576cb5f5cbfa10
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/48079
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/cpu/checker/cpu.hh

@@ -51,7 +51,6 @@
 #include "cpu/base.hh"
 #include "cpu/exec_context.hh"
 #include "cpu/inst_res.hh"
-#include "cpu/o3/dyn_inst.hh"
 #include "cpu/pc_event.hh"
 #include "cpu/simple_thread.hh"
 #include "cpu/static_inst.hh"

src/cpu/o3/cpu.cc

@@ -46,6 +46,7 @@
 #include "cpu/activity.hh"
 #include "cpu/checker/cpu.hh"
 #include "cpu/checker/thread_context.hh"
+#include "cpu/o3/dyn_inst.hh"
 #include "cpu/o3/limits.hh"
 #include "cpu/o3/thread_context.hh"
 #include "cpu/simple_thread.hh"

src/cpu/o3/lsq_unit.cc

@@ -46,6 +46,7 @@
 #include "base/str.hh"
 #include "config/the_isa.hh"
 #include "cpu/checker/cpu.hh"
+#include "cpu/o3/dyn_inst.hh"
 #include "cpu/o3/limits.hh"
 #include "cpu/o3/lsq.hh"
 #include "debug/Activity.hh"