patchworktree: don't use C99 feature

> Commits 9c0b9f6 ("worktree: add 'list' command", 18-09-2015) and
> 40ca3d3 ("worktree: add functions to get worktree details", 18-08-2015)
> both introduce the use of a C99 feature (declare the loop control
> variable in the loop header initializer section).
>
> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
> ---
>
> Hi Junio,
>
> The pu branch doesn't build for me. Do you have -std=c99 set somewhere?
>
> Could you please squash the relevant parts of this patch (or something
> like it) into the two commits mentioned above.
>
> Thanks!

> ATB,
> Ramsay Jones
>
>  builtin/worktree.c | 6 +++---
>  worktree.c         | 7 +++++--
>  2 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/builtin/worktree.c b/builtin/worktree.c
> index e6e36ac..b318c39 100644
> --- a/builtin/worktree.c
> +++ b/builtin/worktree.c
> @@ -415,16 +415,16 @@ static int list(int ac, const char **av, const char *prefix)
>          usage_with_options(worktree_usage, options);
>      else {
>          struct worktree **worktrees = get_worktrees();
> -        int path_maxlen = 0;
> +        int i, path_maxlen = 0;
>  
>          if (!porcelain) {
> -            for (int i = 0; worktrees[i]; i++) {
> +            for (i = 0; worktrees[i]; i++) {
>                  int len = strlen(worktrees[i]->path);
>                  if (len > path_maxlen)
>                      path_maxlen = len;
>              }
>          }
> -        for (int i = 0; worktrees[i]; i++) {
> +        for (i = 0; worktrees[i]; i++) {
>              if (porcelain)
>                  show_worktree_porcelain(worktrees[i]);
>              else
> diff --git a/worktree.c b/worktree.c
> index 41c229e..d17b5b6 100644
> --- a/worktree.c
> +++ b/worktree.c
> @@ -5,7 +5,9 @@
>  
>  void free_worktrees(struct worktree **worktrees)
>  {
> -    for (int i = 0; worktrees[i]; i++) {
> +    int i;
> +
> +    for (i = 0; worktrees[i]; i++) {
>          free(worktrees[i]->path);
>          free(worktrees[i]->git_dir);
>          free(worktrees[i]->head_ref);
> @@ -207,8 +209,9 @@ char *find_shared_symref(const char *symref, const char *target)
>      struct strbuf sb = STRBUF_INIT;
>      struct worktree **worktrees = get_worktrees();
>      int symref_is_head = !strcmp("HEAD", symref);
> +    int i;
>  
> -    for (int i = 0; worktrees[i]; i++) {
> +    for (i = 0; worktrees[i]; i++) {
>          if (!symref_is_head) {
>              strbuf_reset(&path);
>              strbuf_reset(&sb);