x86: delay the export removal of init_mm

delay the removal of this symbol export by one more kernel release,
giving external modules such as VirtualBox a chance to stop using it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/feature-removal-schedule.txt

@@ -316,3 +316,15 @@ Why:	Largely unmaintained and almost entirely unused.  File system
 	is largely pointless as without a lot of work only the most
 	trivial of Solaris binaries can work with the emulation code.
 Who:	David S. Miller <davem@davemloft.net>
+
+---------------------------
+
+What:	init_mm export
+When:	2.6.26
+Why:	Not used in-tree. The current out-of-tree users used it to
+	work around problems in the CPA code which should be resolved
+	by now. One usecase was described to provide verification code
+	of the CPA operation. That's a good idea in general, but such
+	code / infrastructure should be in the kernel and not in some
+	out-of-tree driver.
+Who:	Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/init_task.c

@@ -15,6 +15,7 @@ static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 struct mm_struct init_mm = INIT_MM(init_mm);
+EXPORT_UNUSED_SYMBOL(init_mm); /* will be removed in 2.6.26 */
 
 /*
  * Initial thread structure.