When trying to map a piece of device memory with a cacheability attribue

(e.g.  the graphics aperture on most video cards), don't error if we
failed to set the mtrr but the map succeeded. Instead print a warning (other
osen handle this case similarly).

Libraries shouldn't use fprintf(stderr, ...); but libpciaccess is really
quite poorly designed.

This diff means that mine and drahn's laptops work with xserver 1.5.

ok kettenis@

lib/libpciaccess/src/openbsd_pci.c

@@ -149,7 +149,8 @@ pci_device_openbsd_map_range(struct pci_device *dev,
 		mo.mo_arg[0] = MEMRANGE_SET_UPDATE;
 
 		if (ioctl(aperturefd, MEMRANGE_SET, &mo))
-			return errno;
+			(void)fprintf(stderr, "mtrr set failed: %s\n",
+			    strerror(errno));
 	}
 #endif
 	return 0;