Include directory reorg and makefile updates.

-Convert the include directory over to using bsdmake
 syntax
-Update/add mkfiles
-Modify install(1) so that it can create symlinks
-Update makefiles to use new install(1) options
-Rename /usr/include/ibm to /usr/include/i386
-Create /usr/include/machine symlink to arch header files
-Move vm_i386.h to its new home in the /usr/include/i386
-Update source files to #include the header files at their
 new homes.
-Add new gnu-includes target for building GCC headers

boot/boot.c

@@ -17,8 +17,8 @@ char version[]=		"2.20";
 #include <limits.h>
 #include <string.h>
 #include <errno.h>
-#include <ibm/partition.h>
-#include <ibm/bios.h>
+#include <machine/partition.h>
+#include <machine/bios.h>
 #include <minix/config.h>
 #include <minix/type.h>
 #include <minix/dmap.h>

boot/bootimage.c

@@ -22,7 +22,7 @@
 #include <sys/video.h>
 #include <kernel/const.h>
 #include <kernel/type.h>
-#include <ibm/partition.h>
+#include <machine/partition.h>
 #include "rawfs.h"
 #include "image.h"
 #include "boot.h"