Merge branch 'cw/strbuf-cleanup'

Move functions that are not about pure string manipulation out of
strbuf.[ch]

* cw/strbuf-cleanup:
  strbuf: remove global variable
  path: move related function to path
  object-name: move related functions to object-name
  credential-store: move related functions to credential-store file
  abspath: move related functions to abspath
  strbuf: clarify dependency
  strbuf: clarify API boundary

builtin/am.c

@@ -1284,7 +1284,7 @@ static int parse_mail(struct am_state *state, const char *mail)
 
 	strbuf_addstr(&msg, "\n\n");
 	strbuf_addbuf(&msg, &mi.log_message);
-	strbuf_stripspace(&msg, 0);
+	strbuf_stripspace(&msg, '\0');
 
 	assert(!state->author_name);
 	state->author_name = strbuf_detach(&author_name, NULL);