UPSTREAM: build system: don't run xcompile or git for %clean/%config targets

It takes a long time for no gain: We don't need to update the
submodules, we don't need to fetch the revision, we don't need to find
the compilers, when all we want to do is to manipulate the .config file
or clean the build directory.

BUG=none
BRANCH=none
TEST=none
CQ-DEPEND=CL:432758

Change-Id: I2a2e65d1f5945885b43e32ecb8406f83f973c106
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 0ffef882d8
Original-Change-Id: Ie1bd446a0d49a81e3cccdb56fe2c43ffd83b6c98
Original-Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Reviewed-on: https://review.coreboot.org/18182
Original-Tested-by: build bot (Jenkins)
Original-Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Original-Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://chromium-review.googlesource.com/431983

Makefile

@@ -30,16 +30,6 @@
 ## SUCH DAMAGE.
 ##
 
-# in addition to the dependency below, create the file if it doesn't exist
-# to silence stupid warnings about a file that would be generated anyway.
-$(if $(wildcard .xcompile),,$(eval $(shell util/xcompile/xcompile $(XGCCPATH) > .xcompile || rm -f .xcompile)))
-
-.xcompile: util/xcompile/xcompile
-	rm -f $@
-	$< $(XGCCPATH) > $@.tmp
-	\mv -f $@.tmp $@ 2> /dev/null
-	rm -f $@.tmp
-
 export top := $(CURDIR)
 export src := src
 export srck := $(top)/util/kconfig
@@ -139,6 +129,16 @@ else
 
 include $(DOTCONFIG)
 
+# in addition to the dependency below, create the file if it doesn't exist
+# to silence stupid warnings about a file that would be generated anyway.
+$(if $(wildcard .xcompile)$(NOCOMPILE),,$(eval $(shell util/xcompile/xcompile $(XGCCPATH) > .xcompile || rm -f .xcompile)))
+
+.xcompile: util/xcompile/xcompile
+	rm -f $@
+	$< $(XGCCPATH) > $@.tmp
+	\mv -f $@.tmp $@ 2> /dev/null
+	rm -f $@.tmp
+
 -include .xcompile
 
 ifneq ($(XCOMPILE_COMPLETE),1)