Makefile: Defer normalizing configuration for reproducible builds

The call to genbuild_h needs to happen after xcompile is imported so
that genbuid_h can use iasl as chosen by xcompile. Move the entire
section down to keep things together.

TEST=no more error that util/crossgcc/xgcc/bin/iasl isn't found.

Change-Id: Ia7afd32bd120e5405e65825144b0c30d69931a22
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52292
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/Makefile b/Makefile
index c148c11..a9fbe98 100644
--- a/Makefile
+++ b/Makefile
@@ -20,17 +20,6 @@
 COREBOOT_EXPORTS := COREBOOT_EXPORTS
 COREBOOT_EXPORTS += top src srck obj objutil objk
 
-# reproducible builds
-LANG:=C
-LC_ALL:=C
-TZ:=UTC0
-ifneq ($(NOCOMPILE),1)
-SOURCE_DATE_EPOCH := $(shell $(top)/util/genbuild_h/genbuild_h.sh . | sed -n 's/^.define COREBOOT_BUILD_EPOCH\>.*"\(.*\)".*/\1/p')
-endif
-# don't use COREBOOT_EXPORTS to ensure build steps outside the coreboot build system
-# are reproducible
-export LANG LC_ALL TZ SOURCE_DATE_EPOCH
-
 DOTCONFIG ?= $(top)/.config
 KCONFIG_CONFIG = $(DOTCONFIG)
 KCONFIG_AUTOADS := $(obj)/cb-config.ads
@@ -176,6 +165,17 @@
 	Restarting the build should fix that, or explain the problem)
 endif
 
+# reproducible builds
+LANG:=C
+LC_ALL:=C
+TZ:=UTC0
+ifneq ($(NOCOMPILE),1)
+SOURCE_DATE_EPOCH := $(shell $(top)/util/genbuild_h/genbuild_h.sh . | sed -n 's/^.define COREBOOT_BUILD_EPOCH\>.*"\(.*\)".*/\1/p')
+endif
+# don't use COREBOOT_EXPORTS to ensure build steps outside the coreboot build system
+# are reproducible
+export LANG LC_ALL TZ SOURCE_DATE_EPOCH
+
 ifneq ($(CONFIG_MMX),y)
 CFLAGS_x86_32 += -mno-mmx
 endif