net: Kill skbuff macros from the stone ages.

This kills of HAVE_ALLOC_SKB and HAVE_ALIGNABLE_SKB.

Nothing in-tree uses them and nothing in-tree has used them
since 2.0.x times.
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -29,9 +29,6 @@
 #include <linux/dmaengine.h>
 #include <linux/hrtimer.h>
 
-#define HAVE_ALLOC_SKB		/* For the drivers to know */
-#define HAVE_ALIGNABLE_SKB	/* Ditto 8)		   */
-
 /* Don't change this without changing skb_csum_unnecessary! */
 #define CHECKSUM_NONE 0
 #define CHECKSUM_UNNECESSARY 1