kernel/x86_64: setup a new team in compatibility mode.

* in load_image_internal(), elf32_load_user_image checks whether the binary
format requires the compatibility mode.
* we then set up the flag THREAD_FLAGS_COMPAT_MODE and the address space size.
* the compatibility mode runtime_loader is hardcoded with x86/runtime_loader.
* if needed, the 64-bit flat_args structure is converted in-place to its 32-bit
layout.
* a 32-bit flat_args isn't handled yet (a 32-bit team execs a 64-bit binary).

Change-Id: Ia6a066bde8d1774d85de29b48dc500e27ae9668f

headers/private/kernel/vm/VMAddressSpace.h

@@ -35,6 +35,10 @@ public:
 			addr_t				Base() const			{ return fBase; }
 			addr_t				EndAddress() const		{ return fEndAddress; }
 			size_t				Size() const { return fEndAddress - fBase + 1; }
+			void				SetSize(size_t size) {
+									fEndAddress = fBase + (size - 1);
+									fFreeSpace = size; }
+
 			size_t				FreeSpace() const		{ return fFreeSpace; }
 			bool				IsBeingDeleted() const	{ return fDeleting; }
 

headers/private/system/thread_defs.h

@@ -37,6 +37,10 @@ enum {
 #define THREAD_CREATION_FLAG_DEFER_SIGNALS	0x01
 	// create the thread with signals deferred, i.e. with
 	// user_thread::defer_signals set to 1
+#ifdef _COMPAT_MODE
+#	define THREAD_CREATION_FLAG_COMPAT_MODE	0x02
+	// create the thread with a compatibility mode
+#endif
 
 
 struct thread_creation_attributes {