kbuild: Print errors to stderr

... at least in the top-level Makefile and scripts/link-vmlinux.sh.
There are some more instances of the 'echo <error>; exit 1' pattern in
some arch Makefiles and kconfig.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>

Makefile

@@ -535,11 +535,11 @@ PHONY += include/config/auto.conf
 
 include/config/auto.conf:
 	$(Q)test -e include/generated/autoconf.h -a -e $@ || (		\
-	echo;								\
-	echo "  ERROR: Kernel configuration is invalid.";		\
-	echo "         include/generated/autoconf.h or $@ are missing.";\
-	echo "         Run 'make oldconfig && make prepare' on kernel src to fix it.";	\
-	echo;								\
+	echo >&2;							\
+	echo >&2 "  ERROR: Kernel configuration is invalid.";		\
+	echo >&2 "         include/generated/autoconf.h or $@ are missing.";\
+	echo >&2 "         Run 'make oldconfig && make prepare' on kernel src to fix it.";	\
+	echo >&2 ;							\
 	/bin/false)
 
 endif # KBUILD_EXTMOD
@@ -796,8 +796,8 @@ prepare3: include/config/kernel.release
 ifneq ($(KBUILD_SRC),)
 	@$(kecho) '  Using $(srctree) as source for kernel'
 	$(Q)if [ -f $(srctree)/.config -o -d $(srctree)/include/config ]; then \
-		echo "  $(srctree) is not clean, please run 'make mrproper'"; \
-		echo "  in the '$(srctree)' directory.";\
+		echo >&2 "  $(srctree) is not clean, please run 'make mrproper'"; \
+		echo >&2 "  in the '$(srctree)' directory.";\
 		/bin/false; \
 	fi;
 endif
@@ -971,11 +971,11 @@ else # CONFIG_MODULES
 # ---------------------------------------------------------------------------
 
 modules modules_install: FORCE
-	@echo
-	@echo "The present kernel configuration has modules disabled."
-	@echo "Type 'make config' and enable loadable module support."
-	@echo "Then build a kernel with module support enabled."
-	@echo
+	@echo >&2
+	@echo >&2 "The present kernel configuration has modules disabled."
+	@echo >&2 "Type 'make config' and enable loadable module support."
+	@echo >&2 "Then build a kernel with module support enabled."
+	@echo >&2
 	@exit 1
 
 endif # CONFIG_MODULES

scripts/link-vmlinux.sh

@@ -210,8 +210,8 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
 	mksysmap ${kallsyms_vmlinux} .tmp_System.map
 
 	if ! cmp -s System.map .tmp_System.map; then
-		echo Inconsistent kallsyms data
-		echo echo Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
+		echo >&2 Inconsistent kallsyms data
+		echo >&2 echo Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 		cleanup
 		exit 1
 	fi