Multiboot build system v4

In order to build the multiboot option rom, we need a Makefile and a tool
to sign the rom with.

Both are provided by this patch and mostly taken from the extboot source,
written by Anthony Liguori.

Once built, the resulting binary gets copied to pc-bios automatically.

Building also occurs automatically when on an x86 host.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/configure b/configure
index ebaf03a..a778fa2 100755
--- a/configure
+++ b/configure
@@ -1868,6 +1868,12 @@
 fi
 echo "TOOLS=$tools" >> $config_mak
 
+roms=
+if test "$cpu" = "i386" -o "$cpu" = "x86_64" ; then
+  roms="pc-bios/optionrom"
+fi
+echo "ROMS=$roms" >> $config_mak
+
 if test -f ${config_h}~ ; then
   if cmp -s $config_h ${config_h}~ ; then
     mv ${config_h}~ $config_h
@@ -2230,10 +2236,11 @@
 
 # build tree in object directory if source path is different from current one
 if test "$source_path_used" = "yes" ; then
-    DIRS="tests tests/cris slirp audio block"
+    DIRS="tests tests/cris slirp audio block pc-bios/optionrom"
     FILES="Makefile tests/Makefile"
     FILES="$FILES tests/cris/Makefile tests/cris/.gdbinit"
     FILES="$FILES tests/test-mmap.c"
+    FILES="$FILES pc-bios/optionrom/Makefile"
     for dir in $DIRS ; do
             mkdir -p $dir
     done