m32r: export empty_zero_page

ERROR: "empty_zero_page" [fs/ext4/ext4dev.ko] undefined!
Reported-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>

arch/m32r/kernel/m32r_ksyms.c

@@ -14,6 +14,7 @@
 #include <asm/delay.h>
 #include <asm/irq.h>
 #include <asm/tlbflush.h>
+#include <asm/pgtable.h>
 
 /* platform dependent support */
 EXPORT_SYMBOL(boot_cpu_data);
@@ -65,6 +66,7 @@ EXPORT_SYMBOL(memset);
 EXPORT_SYMBOL(copy_page);
 EXPORT_SYMBOL(clear_page);
 EXPORT_SYMBOL(strlen);
+EXPORT_SYMBOL(empty_zero_page);
 
 EXPORT_SYMBOL(_inb);
 EXPORT_SYMBOL(_inw);