efi_loader: avoid make race condition

When U-Boot is built with 'make -j' there is not guarantee that targets in
directory arch/ are built before targets in directory lib/. The current
build instruction for EFI binaries in lib/ rely on dependencies in arch/.
If $(EFI_CRT0) or $(EFI_RELOC) is not yet built before trying to build
%.efi an error
    *** No rule to make target '%.efi'
occurs.

With the patch separate copies of $(EFI_CRT0) and $(EFI_RELOC) named
efi_crt0.o and efi_reloc.o are built in lib/efi_loader and
lib/efi_selftest.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

scripts/Makefile.lib

@@ -385,8 +385,14 @@ cmd_efi_ld = $(LD) -nostdlib -znocombreloc -T $(EFI_LDS_PATH) -shared \
 
 EFI_LDS_PATH = $(srctree)/arch/$(ARCH)/lib/$(EFI_LDS)
 
-$(obj)/%_efi.so: $(obj)/%.o arch/$(ARCH)/lib/$(EFI_CRT0) \
-		arch/$(ARCH)/lib/$(EFI_RELOC)
+$(obj)/efi_crt0.o: $(srctree)/arch/$(ARCH)/lib/$(EFI_CRT0:.o=.S)
+	$(call if_changed_dep,as_o_S)
+
+$(obj)/efi_reloc.o: $(srctree)/arch/$(ARCH)/lib/$(EFI_RELOC:.o=.c) $(recordmcount_source) FORCE
+	$(call cmd,force_checksrc)
+	$(call if_changed_rule,cc_o_c)
+
+$(obj)/%_efi.so: $(obj)/%.o $(obj)/efi_crt0.o $(obj)/efi_reloc.o
 	$(call cmd,efi_ld)
 
 # ACPI