path: use strbuf_add_real_path()

Avoid a string copy to a static buffer by using strbuf_add_real_path()
instead of combining strbuf_addstr() and real_path().

Patch generated by Coccinelle and contrib/coccinelle/strbuf.cocci.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

path.c

@@ -717,7 +717,7 @@ char *expand_user_path(const char *path, int real_home)
 			if (!home)
 				goto return_null;
 			if (real_home)
-				strbuf_addstr(&user_path, real_path(home));
+				strbuf_add_real_path(&user_path, home);
 			else
 				strbuf_addstr(&user_path, home);
 #ifdef GIT_WINDOWS_NATIVE