Merge utils make check_severity_db: say ERROR for failing the build

utils `make check_severity_db` will fail the build if a (probably new) capability in not listed in severity.db. This also means it should print out an ERROR, not a warning.

This is a follow-up of lp#1890547 and !589

MR: !591


Acked-by: John Johansen <john.johansen@canonical.com>
(cherry picked from commit 2f5d5e1b)
Signed-off-by: John Johansen <john.johansen@canonical.com>

utils/Makefile

@@ -82,7 +82,7 @@ check_severity_db: /usr/include/linux/capability.h severity.db
 	# The sed statement is based on the one in the parser's makefile
 	RC=0 ; for cap in $(shell ../common/list_capabilities.sh) ; do \
 	    if !  grep -q -w $${cap} severity.db ; then \
-		echo "Warning! capability $${cap} not found in severity.db" ; \
+		echo "ERROR: capability $${cap} not found in severity.db" ; \
 		RC=1 ; \
 	    fi ;\
 	done ; \