Add always_inline attribute to force gcc to inline single-instruction

functions.

src/include/gpxe/job.h

  * @v intf		Generic object communication interface
  * @ret job		Job control interface
  */
-static inline struct job_interface *
+static inline __attribute__ (( always_inline )) struct job_interface *
 intf_to_job ( struct interface *intf ) {
 	return container_of ( intf, struct job_interface, intf );
 }
  * @v job		Job control interface
  * @ret dest		Destination interface
  */
-static inline struct job_interface *
+static inline __attribute__ (( always_inline )) struct job_interface *
 job_dest ( struct job_interface *job ) {
 	return intf_to_job ( job->intf.dest );
 }

src/include/gpxe/xfer.h

  * @v intf		Generic object communication interface
  * @ret xfer		Data transfer interface
  */
-static inline struct xfer_interface *
+static inline __attribute__ (( always_inline )) struct xfer_interface *
 intf_to_xfer ( struct interface *intf ) {
 	return container_of ( intf, struct xfer_interface, intf );
 }
  * @v xfer		Data transfer interface
  * @ret dest		Destination interface
  */
-static inline struct xfer_interface *
+static inline __attribute__ (( always_inline )) struct xfer_interface *
 xfer_dest ( struct xfer_interface *xfer ) {
 	return intf_to_xfer ( xfer->intf.dest );
 }