https://bugs.gentoo.org/970041

In binutils 2.46, objcopy became more strict with what it accepts as target.

--- a/Make.common
+++ b/Make.common
@@ -121,8 +121,8 @@
 # objcopy flags for GNU-EFI
 #
 
-FORMAT          = --target=efi-app-$(ARCH)
-FORMAT_DRIVER   = --target=efi-bsdrv-$(ARCH)
+FORMAT          = --output-target=efi-app-$(ARCH)
+FORMAT_DRIVER   = --output-target=efi-bsdrv-$(ARCH)
 
 #
 # Modifications on a per-architecture basis....