use strbuf_addbuf() for appending a strbuf to another

Use strbuf_addbuf() where possible; it's shorter and more efficient.
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

dir.c

@@ -2346,7 +2346,7 @@ void write_untracked_extension(struct strbuf *out, struct untracked_cache *untra
 
 	varint_len = encode_varint(untracked->ident.len, varbuf);
 	strbuf_add(out, varbuf, varint_len);
-	strbuf_add(out, untracked->ident.buf, untracked->ident.len);
+	strbuf_addbuf(out, &untracked->ident);
 
 	strbuf_add(out, ouc, ouc_size(len));
 	free(ouc);

path.c

@@ -246,7 +246,7 @@ static void do_submodule_path(struct strbuf *buf, const char *path,
 		strbuf_addstr(buf, git_dir);
 	}
 	strbuf_addch(buf, '/');
-	strbuf_addstr(&git_submodule_dir, buf->buf);
+	strbuf_addbuf(&git_submodule_dir, buf);
 
 	strbuf_vaddf(buf, fmt, args);
 

wt-status.c

@@ -1060,7 +1060,7 @@ static void abbrev_sha1_in_line(struct strbuf *line)
 			strbuf_addf(split[1], "%s ", abbrev);
 			strbuf_reset(line);
 			for (i = 0; split[i]; i++)
-				strbuf_addf(line, "%s", split[i]->buf);
+				strbuf_addbuf(line, split[i]);
 		}
 	}
 	for (i = 0; split[i]; i++)