Add the size field to the ivar structure.

This was the last change made to the ABI before upstreaming the clang
parts.

ivar.h

@@ -22,6 +22,10 @@ struct objc_ivar
 	 * offset from the object pointer.
 	 */
 	int        *offset;
+	/**
+	 * The size of this ivar.  Note that the current ABI limits ivars to 4GB.
+	 */
+	uint32_t    size;
 	/**
 	 * Flags for this instance variable.
 	 */