x86-32: Export kernel_stack_pointer() for modules

Modules, in particular oprofile (and possibly other similar tools)
need kernel_stack_pointer(), so export it using EXPORT_SYMBOL_GPL().

Cc: Yang Wei <wei.yang@windriver.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Jun Zhang <jun.zhang@intel.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20120912135059.GZ8285@erda.amd.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/kernel/ptrace.c

@@ -22,6 +22,7 @@
 #include <linux/perf_event.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/rcupdate.h>
+#include <linux/module.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -193,6 +194,7 @@ unsigned long kernel_stack_pointer(struct pt_regs *regs)
 
 	return (unsigned long)regs;
 }
+EXPORT_SYMBOL_GPL(kernel_stack_pointer);
 
 static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long regno)
 {