sim,mem,dev: Merge eventq_impl.hh into eventq.hh.

Having some methods (which are supposed to be inline) defined in another
file which is only included sometimes creates a lot of opportunities for
errors. They no longer need to be separate, so merge them together.

Change-Id: I5846e55f53f59b9c2081680a6441659265a765f7
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/29409
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/dev/intel_8254_timer.hh

@@ -36,7 +36,7 @@
 #include "base/types.hh"
 #include "base/trace.hh"
 #include "debug/Intel8254Timer.hh"
-#include "sim/eventq_impl.hh"
+#include "sim/eventq.hh"
 #include "sim/serialize.hh"
 
 /** Programmable Interval Timer (Intel 8254) */

src/dev/mc146818.hh

@@ -32,7 +32,7 @@
 #include "base/bitunion.hh"
 #include "base/logging.hh"
 #include "sim/core.hh"
-#include "sim/eventq_impl.hh"
+#include "sim/eventq.hh"
 
 /** Real-Time Clock (MC146818) */
 class MC146818 : public EventManager