[build] Add everything target

The everything target builds multiple image types on each supported
arch/platform combination.

Signed-off-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/Makefile

 # Default build target: build the most common targets and print out a
 # helpfully suggestive message
 #
-all : bin/blib.a bin/ipxe.dsk bin/ipxe.iso bin/ipxe.usb bin/undionly.kpxe \
-      bin/rtl8139.rom
+ALL		:= bin/blib.a bin/ipxe.dsk bin/ipxe.iso bin/ipxe.usb \
+		   bin/undionly.kpxe bin/rtl8139.rom
+all : $(ALL)
 	@$(ECHO) '==========================================================='
 	@$(ECHO)
 	@$(ECHO) 'To create a bootable floppy, type'
 	@$(ECHO)
 	@$(ECHO) '==========================================================='
 
+###############################################################################
+#
+# Comprehensive build target: build a selection of cross-platform
+# targets to expose potential build errors that show up only on
+# certain platforms
+#
+everything :
+	$(Q)$(MAKE) --no-print-directory $(ALL) \
+		bin-i386-efi/ipxe.efi bin-i386-efi/ipxe.efidrv \
+		bin-i386-efi/ipxe.efirom \
+		bin-x86_64-efi/ipxe.efi bin-x86_64-efi/ipxe.efidrv \
+		bin-x86_64-efi/ipxe.efirom
+
 ###############################################################################
 #
 # Build targets that do nothing but might be tried by users