misc: Fix a few accidental transitive includes.

Some files depend on definitions from files that they weren't including
themselves. They were working accidentally by getting those definitions
transitively through other, unrelated headers.

Change-Id: I50c919a4eb6c4484d4ee6b7f4fe02f075132964d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36282
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/dev/arm/timer_a9global.hh

@@ -39,6 +39,7 @@
 #ifndef __DEV_ARM_GLOBAL_TIMER_HH__
 #define __DEV_ARM_GLOBAL_TIMER_HH__
 
+#include "base/bitunion.hh"
 #include "dev/io_device.hh"
 #include "params/A9GlobalTimer.hh"
 

src/dev/ps2/mouse.hh

@@ -41,6 +41,7 @@
 #ifndef __DEV_PS2_MOUSE_HH__
 #define __DEV_PS2_MOUSE_HH__
 
+#include "base/bitunion.hh"
 #include "dev/ps2/device.hh"
 
 struct PS2MouseParams;

src/dev/x86/i8042.hh

@@ -31,6 +31,7 @@
 
 #include <deque>
 
+#include "base/bitunion.hh"
 #include "dev/intpin.hh"
 #include "dev/io_device.hh"
 #include "dev/ps2/device.hh"