http: mark unused parameters in curl callbacks

These functions are all used as callbacks for curl, so they have to
conform to a particular interface. But they don't need all of their
parameters:

  - fwrite_null() throws away the input, so it doesn't look at most
    parameters

  - fwrite_wwwauth() in theory could take the auth struct in its void
    pointer, but instead we just access it as the global http_auth
    (matching the rest of the code in this file)

  - curl_trace() always writes via the trace mechanism, so it doesn't
    need its void pointer to know where to send things. Likewise, it
    ignores the CURL parameter, since nothing we trace requires querying
    the handle.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -196,7 +196,7 @@ static inline int is_hdr_continuation(const char *ptr, const size_t size)
 	return size && (*ptr == ' ' || *ptr == '\t');
 }
 
-static size_t fwrite_wwwauth(char *ptr, size_t eltsize, size_t nmemb, void *p)
+static size_t fwrite_wwwauth(char *ptr, size_t eltsize, size_t nmemb, void *p UNUSED)
 {
 	size_t size = eltsize * nmemb;
 	struct strvec *values = &http_auth.wwwauth_headers;
@@ -295,7 +295,8 @@ exit:
 	return size;
 }
 
-size_t fwrite_null(char *ptr, size_t eltsize, size_t nmemb, void *strbuf)
+size_t fwrite_null(char *ptr UNUSED, size_t eltsize UNUSED, size_t nmemb,
+		   void *data UNUSED)
 {
 	return nmemb;
 }
@@ -821,7 +822,9 @@ static void curl_dump_info(char *data, size_t size)
 	strbuf_release(&buf);
 }
 
-static int curl_trace(CURL *handle, curl_infotype type, char *data, size_t size, void *userp)
+static int curl_trace(CURL *handle UNUSED, curl_infotype type,
+		      char *data, size_t size,
+		      void *userp UNUSED)
 {
 	const char *text;
 	enum { NO_FILTER = 0, DO_FILTER = 1 };