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.

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

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)

Makefile.inc

@@ -13,7 +13,11 @@
 ## GNU General Public License for more details.
 ##
 
+ifneq ($(NOCOMPILE),1)
 GIT:=$(shell [ -e "$(top)/.git" ] && command -v git)
+else
+GIT:=
+endif
 
 #######################################################################
 # normalize Kconfig variables in a central place

payloads/coreinfo/Makefile

@@ -20,6 +20,7 @@ srck := $(src)/../../util/kconfig
 coreinfo_obj := $(src)/build
 objk := $(src)/build/util/kconfig
 
+ifeq ($(filter %clean,$(MAKECMDGOALS)),)
 export KERNELVERSION      := 0.1.0
 export KCONFIG_AUTOHEADER := $(coreinfo_obj)/config.h
 export KCONFIG_AUTOCONFIG := $(coreinfo_obj)/auto.conf
@@ -128,6 +129,12 @@ $(coreinfo_obj)/config.h:
 
 $(shell mkdir -p $(coreinfo_obj) $(objk)/lxdialog $(KCONFIG_SPLITCONFIG))
 
+include $(srck)/Makefile
+
+.PHONY: $(PHONY) prepare
+
+else
+
 clean:
 	rm -rf build/*.elf build/*.o .xcompile
 
@@ -135,6 +142,5 @@ distclean: clean
 	rm -rf build lpbuild
 	rm -f .config* lp.config*
 
-include $(srck)/Makefile
+.PHONY: clean distclean
-
+endif
-.PHONY: $(PHONY) prepare clean distclean

payloads/libpayload/Makefile

@@ -81,14 +81,6 @@ DOXYGEN_OUTPUT_DIR := doxygen
 
 all: real-all
 
-# 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 $(top)/../../util/xcompile/xcompile $(XGCCPATH) > .xcompile)))
-
-.xcompile: $(top)/../../util/xcompile/xcompile
-	$< $(XGCCPATH) > $@.tmp
-	\mv -f $@.tmp $@ 2> /dev/null
-
 ifeq ($(INNER_SCANBUILD),y)
 CC:=$(CC_real)
 HOSTCC:=$(CC_real) --hostcc
@@ -101,8 +93,6 @@ include $(srck)/Makefile
 
 include $(HAVE_DOTCONFIG)
 
-include .xcompile
-
 ARCHDIR-$(CONFIG_LP_ARCH_ARM)     := arm
 ARCHDIR-$(CONFIG_LP_ARCH_ARM64)   := arm64
 ARCHDIR-$(CONFIG_LP_ARCH_MIPS)    := mips
@@ -138,7 +128,7 @@ ifeq ($(strip $(HAVE_DOTCONFIG)),)
 NOCOMPILE:=1
 endif
 ifneq ($(MAKECMDGOALS),)
-ifneq ($(filter %config distclean,$(MAKECMDGOALS)),)
+ifneq ($(filter %config %clean,$(MAKECMDGOALS)),)
 NOCOMPILE:=1
 endif
 endif
@@ -149,6 +139,16 @@ real-all: config
 
 else
 
+# 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 $(top)/../../util/xcompile/xcompile $(XGCCPATH) > .xcompile)))
+
+.xcompile: $(top)/../../util/xcompile/xcompile
+	$< $(XGCCPATH) > $@.tmp
+	\mv -f $@.tmp $@ 2> /dev/null
+
+-include .xcompile
+
 ifneq ($(INNER_SCANBUILD),y)
 ifeq ($(CONFIG_LP_COMPILER_LLVM_CLANG),y)
 CC:=clang -m32