tags: fix `make tags` target for out of tree builds

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Todd Short <todd.short@me.com>
(Merged from https://github.com/openssl/openssl/pull/21079)

Configurations/unix-Makefile.tmpl

@@ -1381,7 +1381,7 @@ test_ordinals:
 
 tags TAGS: FORCE
 	rm -f TAGS tags
-	-util/ctags.sh
+	-( cd $(SRCDIR); util/ctags.sh )
 	-etags `find . -name '*.[ch]' -o -name '*.pm'`
 
 providers/fips.checksum.new: providers/fips.module.sources.new