patchhttp: fix an unused variable warning for 'curl_no_proxy'

> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
> ---
>
> Hi Junio,
>
> I happened to be building git on an _old_ laptop earlier this evening
> and gcc complained, thus:
>
>       CC http.o
>   http.c:77:20: warning: ‘curl_no_proxy’ defined but not used [-Wunused-variable]
>    static const char *curl_no_proxy;
>                       ^
> The version of libcurl installed was 0x070f04. So, while it was fresh in my
> mind, I applied and tested this patch.

> ATB,
> Ramsay Jones
> 
>  http.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/http.c b/http.c
> index 8c11156ae..a5bd5d62c 100644
> --- a/http.c
> +++ b/http.c
> @@ -69,6 +69,9 @@ static const char *ssl_key;
>  #if LIBCURL_VERSION_NUM >= 0x070908
>  static const char *ssl_capath;
>  #endif
> +#if LIBCURL_VERSION_NUM >= 0x071304
> +static const char *curl_no_proxy;
> +#endif
>  #if LIBCURL_VERSION_NUM >= 0x072c00
>  static const char *ssl_pinnedkey;
>  #endif
> @@ -77,7 +80,6 @@ static long curl_low_speed_limit = -1;
>  static long curl_low_speed_time = -1;
>  static int curl_ftp_no_epsv;
>  static const char *curl_http_proxy;
> -static const char *curl_no_proxy;
>  static const char *http_proxy_authmethod;
>  static struct {
>  	const char *name;

> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
> ---
> 
> Hi Junio,
> 
> I happened to be building git on an _old_ laptop earlier this evening
> and gcc complained, thus:
> 
>       CC http.o
>   http.c:77:20: warning: ‘curl_no_proxy’ defined but not used [-Wunused-variable]
>    static const char *curl_no_proxy;
>                       ^
> The version of libcurl installed was 0x070f04. So, while it was fresh in my
> mind, I applied and tested this patch.

> diff --git a/http.c b/http.c
> index 8c11156ae..a5bd5d62c 100644
> --- a/http.c
> +++ b/http.c
> @@ -69,6 +69,9 @@ static const char *ssl_key;
>  #if LIBCURL_VERSION_NUM >= 0x070908
>  static const char *ssl_capath;
>  #endif
> +#if LIBCURL_VERSION_NUM >= 0x071304
> +static const char *curl_no_proxy;
> +#endif
>  #if LIBCURL_VERSION_NUM >= 0x072c00
>  static const char *ssl_pinnedkey;
>  #endif
> @@ -77,7 +80,6 @@ static long curl_low_speed_limit = -1;
>  static long curl_low_speed_time = -1;
>  static int curl_ftp_no_epsv;
>  static const char *curl_http_proxy;
> -static const char *curl_no_proxy;

> On Wed, Mar 14, 2018 at 09:56:06PM +0000, Ramsay Jones wrote:
> 
>> Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
>> ---
>>
>> Hi Junio,
>>
>> I happened to be building git on an _old_ laptop earlier this evening
>> and gcc complained, thus:
>>
>>       CC http.o
>>   http.c:77:20: warning: ‘curl_no_proxy’ defined but not used [-Wunused-variable]
>>    static const char *curl_no_proxy;
>>                       ^
>> The version of libcurl installed was 0x070f04. So, while it was fresh in my
>> mind, I applied and tested this patch.
> 
> Makes sense. This #if would go away under my "do not support antique
> curl versions" proposal. I haven't really pushed that forward since Tom
> Christensen's patches to actually make the thing build (and presumably
> since he is building on antique versions he can't turn on -Werror
> anyway, since IIRC it tends to have some false positives).

> I agree with Jonathan that this explanation should be in the commit
> message. The patch itself looks OK, although:
> 
>> diff --git a/http.c b/http.c
>> index 8c11156ae..a5bd5d62c 100644
>> --- a/http.c
>> +++ b/http.c
>> @@ -69,6 +69,9 @@ static const char *ssl_key;
>>  #if LIBCURL_VERSION_NUM >= 0x070908
>>  static const char *ssl_capath;
>>  #endif
>> +#if LIBCURL_VERSION_NUM >= 0x071304
>> +static const char *curl_no_proxy;
>> +#endif
>>  #if LIBCURL_VERSION_NUM >= 0x072c00
>>  static const char *ssl_pinnedkey;
>>  #endif
>> @@ -77,7 +80,6 @@ static long curl_low_speed_limit = -1;
>>  static long curl_low_speed_time = -1;
>>  static int curl_ftp_no_epsv;
>>  static const char *curl_http_proxy;
>> -static const char *curl_no_proxy;
> 
> I'm not sure whether our ordering of these variables actually means
> much, but arguably it makes sense to keep the proxy-related variables
> near each other, even if one of them has to be surrounded by an #if.
> 
> I guess you were going for ordering the #if's in increasing version
> order. I'm not sure the existing code follows that pattern very well.

> >> The version of libcurl installed was 0x070f04. So, while it was fresh in my
> >> mind, I applied and tested this patch.
> > 
> > Makes sense. This #if would go away under my "do not support antique
> > curl versions" proposal. I haven't really pushed that forward since Tom
> > Christensen's patches to actually make the thing build (and presumably
> > since he is building on antique versions he can't turn on -Werror
> > anyway, since IIRC it tends to have some false positives).
> 
> Yes, I suspected this would be removed by your proposed update (hence
> the cc:), but I didn't know what the ETA on your patches was. Is this
> worth doing, or are you about to re-visit that series?

> > I'm not sure whether our ordering of these variables actually means
> > much, but arguably it makes sense to keep the proxy-related variables
> > near each other, even if one of them has to be surrounded by an #if.
> > 
> > I guess you were going for ordering the #if's in increasing version
> > order. I'm not sure the existing code follows that pattern very well.
> 
> Yes, that was the idea, but I was already in two minds about that!
> In the end I went with this, because not all of the proxy variables
> are together anyway. ;-) (see, for example, 'proxy_auth' and 
> 'curl_proxyuserpwd' around line #113).
> 
> So, I don't mind placing the #ifdef around the current definition
> (rather than moving it up), if you would prefer that. (It will have
> to be tomorrow, since I have put that laptop away now!).