make: don't run feature-tests for tags/etags/cscope

Each `make tags` resulted in running feature-tests.
That's not needed for tags generation.
Don't waste time on tests as we don't compile anything.
Reported-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

Makefile

@@ -167,7 +167,7 @@ criu-deps	+= include/common/asm
 #
 # Configure variables.
 export CONFIG_HEADER := criu/include/config.h
-ifeq ($(filter clean mrproper,$(MAKECMDGOALS)),)
+ifeq ($(filter tags etags cscope clean mrproper,$(MAKECMDGOALS)),)
 include Makefile.config
 else
 # To clean all files, enable make/build options here