powerpc: Merge enough to start building in arch/powerpc.

This creates the directory structure under arch/powerpc and a bunch
of Kconfig files.  It does a first-cut merge of arch/powerpc/mm,
arch/powerpc/lib and arch/powerpc/platforms/powermac.  This is enough
to build a 32-bit powermac kernel with ARCH=powerpc.

For now we are getting some unmerged files from arch/ppc/kernel and
arch/ppc/syslib, or arch/ppc64/kernel.  This makes some minor changes
to files in those directories and files outside arch/powerpc.

The boot directory is still not merged.  That's going to be interesting.

Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/lib/usercopy.c

@@ -0,0 +1,41 @@
+/*
+ * Functions which are too large to be inlined.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include <linux/module.h>
+#include <asm/uaccess.h>
+
+unsigned long copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	if (likely(access_ok(VERIFY_READ, from, n)))
+		n = __copy_from_user(to, from, n);
+	else
+		memset(to, 0, n);
+	return n;
+}
+
+unsigned long copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	if (likely(access_ok(VERIFY_WRITE, to, n)))
+		n = __copy_to_user(to, from, n);
+	return n;
+}
+
+unsigned long copy_in_user(void __user *to, const void __user *from,
+			   unsigned long n)
+{
+	might_sleep();
+	if (likely(access_ok(VERIFY_READ, from, n) &&
+	    access_ok(VERIFY_WRITE, to, n)))
+		n =__copy_tofrom_user(to, from, n);
+	return n;
+}
+
+EXPORT_SYMBOL(copy_from_user);
+EXPORT_SYMBOL(copy_to_user);
+EXPORT_SYMBOL(copy_in_user);
+