[legal] Add a selection of FILE_LICENCE declarations

Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.

src/arch/i386/interface/pxe/pxe_call.c

@@ -16,6 +16,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <gpxe/uaccess.h>
 #include <registers.h>
 #include <biosint.h>

src/arch/i386/interface/pxe/pxe_entry.S

@@ -17,6 +17,8 @@
  *
  */
 
+FILE_LICENCE ( GPL2_OR_LATER )
+
 	.arch i386
 
 /****************************************************************************

src/arch/i386/interface/pxe/pxe_file.c

@@ -31,6 +31,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 FEATURE ( FEATURE_MISC, "PXEXT", DHCP_EB_FEATURE_PXE_EXT, 2 );
 
 /**

src/arch/i386/interface/pxe/pxe_loader.c

@@ -16,6 +16,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <gpxe/init.h>
 #include "pxe.h"
 #include "pxe_call.h"

src/arch/i386/interface/pxe/pxe_preboot.c

@@ -23,6 +23,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <stdint.h>
 #include <string.h>
 #include <stdlib.h>

src/arch/i386/interface/pxe/pxe_tftp.c

@@ -22,6 +22,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <stdlib.h>
 #include <stdio.h>
 #include <errno.h>

src/arch/i386/interface/pxe/pxe_udp.c

@@ -30,6 +30,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 /** A PXE UDP connection */
 struct pxe_udp_connection {
 	/** Data transfer interface to UDP stack */

src/arch/i386/interface/pxe/pxe_undi.c

@@ -22,6 +22,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>