add netboot support.

netboot/Makefile.am

@@ -0,0 +1,20 @@
+
+# For <stage1.h>.
+INCLUDES = -I$(top_srcdir)/stage1
+
+if NETBOOT_SUPPORT
+LIBDRIVERS = libdrivers.a
+else
+LIBDRIVERS =
+endif
+
+noinst_LIBRARIES = $(LIBDRIVERS)
+
+DRIVERS = 3c509.c 3c509.h 3c59x.c cs89x0.c cs89x0.h eepro100.c \
+	lance.c ns8390.c ns8390.h
+
+libdrivers_a_SOURCES = byteorder.h config.c config.h fsys_tftp.c \
+	if.h io.h ip.c ip.h netboot.h netdevice.h nic.h pci.c pci.h \
+	$(DRIVERS)
+libdrivers_a_CFLAGS = $(STAGE2_CFLAGS) -fno-builtin -nostdinc \
+	-DFSYS_TFTP $(NET_CFLAGS) $(NET_EXTRAFLAGS)