Stick to old ABI for gnu-efi > 3.0.18

gnu-efi introduced some ABI changes for the upcoming 4.0 release, see
https://github.com/ncroxon/gnu-efi/blob/master/docs/README.ABI.md

For now, stick to the old API/ABI so to support older gnu-efi versions
without #ifdef'ing the codebase.

Signed-off-by: Christian Storm <[email protected]>
Signed-off-by: Jan Kiszka <[email protected]>

Author: stormc

Makefile.am

@@ -221,6 +221,7 @@ efi_cflags = \
 	-fno-stack-protector \
 	-Wsign-compare \
 	-DGNU_EFI_USE_MS_ABI \
+	-DGNU_EFI_3_0_COMPAT \
 	-Werror \
 	$(CFLAGS_MGENERAL_REGS_ONLY) \
 	$(CFLAGS)