[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/x86/include/bits/pci_io.h

@@ -7,6 +7,8 @@
  *
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <gpxe/pcibios.h>
 #include <gpxe/pcidirect.h>
 

src/arch/x86/include/bits/string.h

@@ -21,6 +21,8 @@
  *		consider these trivial functions to be PD.
  */
 
+FILE_LICENCE ( PUBLIC_DOMAIN );
+
 #define __HAVE_ARCH_MEMCPY
 
 extern void * __memcpy ( void *dest, const void *src, size_t len );

src/arch/x86/include/gpxe/efi/efix86_nap.h

@@ -7,6 +7,8 @@
  *
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #ifdef NAP_EFIX86
 #define NAP_PREFIX_efix86
 #else

src/arch/x86/include/gpxe/pcibios.h

@@ -9,6 +9,8 @@
  *
  */
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #ifdef PCIAPI_PCBIOS
 #define PCIAPI_PREFIX_pcbios
 #else

src/arch/x86/include/gpxe/pcidirect.h

@@ -1,6 +1,8 @@
 #ifndef _PCIDIRECT_H
 #define _PCIDIRECT_H
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 #include <stdint.h>
 #include <gpxe/io.h>