X.509: shut up about included cert for silent build

Every kernel build that includes X.509 support prints out
a message like

 - Including cert signing_key.x509

This may be useful for some cases, but when doing automated
build tests, it just means noise.

To hide the message, this uses '$(kecho)' for printing the
message, which means we still see it when building with V=1,
but not at the normal level or when building with 'make -s'.
Signed-off-by: Arnd Bergmann <arnd@arnd.de>
Signed-off-by: David Howells <dhowells@redhat.com>

kernel/Makefile

@@ -142,7 +142,7 @@ endif
 kernel/system_certificates.o: $(obj)/x509_certificate_list
 
 quiet_cmd_x509certs  = CERTS   $@
-      cmd_x509certs  = cat $(X509_CERTIFICATES) /dev/null >$@ $(foreach X509,$(X509_CERTIFICATES),; echo "  - Including cert $(X509)")
+      cmd_x509certs  = cat $(X509_CERTIFICATES) /dev/null >$@ $(foreach X509,$(X509_CERTIFICATES),; $(kecho) "  - Including cert $(X509)")
 
 targets += $(obj)/x509_certificate_list
 $(obj)/x509_certificate_list: $(X509_CERTIFICATES) $(obj)/.x509.list