This patch is required to fix compile errors for m32r.
This was originally given by the following patch:
[PATCH] move irq_enter and irq_exit to common code
http://www.ussg.iu.edu/hypermail/linux/kernel/0411.1/1738.html
I think it was maybe accidentally dropped only for the m32r arch due to a
patching conflict with the other patches or something like that.