kernel: add a compatibility commpage on x86_64.

* x86 uses a commpage with 32-bit addresses, incompatible with the one used for
x86_64. For this reason, a compatibility commpage is needed to support a 32-bit
userland on x86_64.
* define ADDRESS_TYPE as a macro for addr_t (default) or uint32 (for the 32-bit
commpage).
* team_create_thread_start_internal() will use clone_commpage_area() with
KERNEL_USER_DATA_BASE or clone_commpage_compat_area() with
KERNEL_USER32_DATA_BASE, to setup the correct commpage.
* real_time_clock (in compatibility mode) also updates the compatibility
commpage with real time data.

Change-Id: I61605077ce0beabab4439ef54edd1eae26f26fd2

headers/private/system/arch/x86/arch_real_time_data.h

@@ -1,4 +1,5 @@
 /*
+ * Copyright 2018 Haiku Inc. All Rights Reserved.
  * Copyright 2006, Ingo Weinhold <[email protected]>.
  * All rights reserved. Distributed under the terms of the MIT License.
  */
@@ -12,6 +13,7 @@
 struct arch_real_time_data {
 	bigtime_t	system_time_offset;
 	uint32		system_time_conversion_factor;
+	uint32		_padding;
 };
 
 #endif	/* _KERNEL_ARCH_REAL_TIME_DATA_H */

headers/private/system/commpage_defs.h

@@ -1,4 +1,5 @@
 /*
+ * Copyright 2018 Haiku Inc. All Rights Reserved.
  * Copyright 2007, Travis Geiselbrecht. All rights reserved.
  * Distributed under the terms of the MIT License.
  */
@@ -19,6 +20,10 @@
 #define COMMPAGE_SIGNATURE 'COMM'
 #define COMMPAGE_VERSION 1
 
+#ifdef COMMPAGE_COMPAT
+#include <arch/x86/arch_commpage_defs.h>
+#else
 #include <arch_commpage_defs.h>
+#endif
 
 #endif	/* _SYSTEM_COMMPAGE_DEFS_H */