From: Ivan Kokshaysky <ink@jurassic.park.msu.ru>

Again...  This time due to pci.h->dmapool.h->io.h included in core logic
files before __EXTERN_INLINE definition.

To prevent such troubles in the future, make io.h/core_xx.h included before
anything else.  Also, this allows to get rid of some duplicated #include's.