Fix osx-gcc CI build failures

[dscho]

The osx-gcc job fails with compiler errors due to the now-stricter type checks in the curl_easy_setopt() calls. There is an upstream contribution already to fix this in Git's own main branch, but those patches to not apply cleanly on top of vfs-2.49.0, therefore I backported them.

Range-diff

• 1: 6f11c42 ! 1: 3b1e099 curl: fix integer constant typechecks with curl_easy_setopt()

  @@ Commit message
   
       We can fix it by just marking the constants with a long "L".
   
  +    Backported-from: 6f11c42e8edc (curl: fix integer constant typechecks with curl_easy_setopt(), 2025-06-04)
       Signed-off-by: Jeff King <[email protected]>
       Signed-off-by: Junio C Hamano <[email protected]>
  +    Signed-off-by: Johannes Schindelin <[email protected]>
   
    ## http-push.c ##
   @@ http-push.c: static char *xml_entities(const char *s)
  @@ http-push.c: static char *xml_entities(const char *s)
    	curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fwrite_null);
   
    ## http.c ##
  +@@ http.c: static int has_proxy_cert_password(void)
  + 
  + static void set_curl_keepalive(CURL *c)
  + {
  +-	curl_easy_setopt(c, CURLOPT_TCP_KEEPALIVE, 1);
  ++	curl_easy_setopt(c, CURLOPT_TCP_KEEPALIVE, 1L);
  + }
  + 
  + /* Return 1 if redactions have been made, 0 otherwise. */
   @@ http.c: static CURL *get_curl_handle(void)
    		die("curl_easy_init failed");
    
  @@ http.c: static CURL *get_curl_handle(void)
    
    	if (curl_ssl_try)
    		curl_easy_setopt(result, CURLOPT_USE_SSL, CURLUSESSL_TRY);
  -@@ http.c: static CURL *get_curl_handle(void)
  - 	}
  - 	init_curl_proxy_auth(result);
  - 
  --	curl_easy_setopt(result, CURLOPT_TCP_KEEPALIVE, 1);
  -+	curl_easy_setopt(result, CURLOPT_TCP_KEEPALIVE, 1L);
  - 
  - 	if (curl_tcp_keepidle > -1)
  - 		curl_easy_setopt(result, CURLOPT_TCP_KEEPIDLE,
   
    ## remote-curl.c ##
   @@ remote-curl.c: static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)

• 2: 30325e2 ! 2: ecd7e78 curl: fix integer variable typechecks with curl_easy_setopt()

  @@ Commit message
       going on obvious. There aren't that many spots to modify (and as you can
       see from the context, we already have some similar casts).
   
  +    Backported-from: 30325e23ba0d (curl: fix integer variable typechecks with curl_easy_setopt(), 2025-06-04)
       Signed-off-by: Jeff King <[email protected]>
       Signed-off-by: Junio C Hamano <[email protected]>
  +    Signed-off-by: Johannes Schindelin <[email protected]>
   
    ## imap-send.c ##
   @@ imap-send.c: static CURL *setup_curl(struct imap_server_conf *srvc, struct credential *cred)

• 3: 4558c8f ! 3: a53e8f6 curl: fix symbolic constant typechecks with curl_easy_setopt()

  @@ Commit message
       dig, as it doesn't really matter: we have to follow what existing curl
       versions ask for anyway.
   
  +    Backported-from: 4558c8f84b2f (curl: fix symbolic constant typechecks with curl_easy_setopt(), 2025-06-04)
       Signed-off-by: Jeff King <[email protected]>
       Signed-off-by: Junio C Hamano <[email protected]>
  +    Signed-off-by: Johannes Schindelin <[email protected]>
   
    ## http.c ##
   @@ http.c: static CURL *get_curl_handle(void)
  - 
  - 	if (http_ssl_backend && !strcmp("schannel", http_ssl_backend) &&
  - 	    !http_schannel_check_revoke) {
  --		curl_easy_setopt(result, CURLOPT_SSL_OPTIONS, CURLSSLOPT_NO_REVOKE);
  -+		curl_easy_setopt(result, CURLOPT_SSL_OPTIONS, (long)CURLSSLOPT_NO_REVOKE);
  - 	}
  - 
  - 	if (http_proactive_auth != PROACTIVE_AUTH_NONE)
  -@@ http.c: static CURL *get_curl_handle(void)
    	}
    
    	curl_easy_setopt(result, CURLOPT_MAXREDIRS, 20L);

• 4: 80de749 = 4: 560fdc1 curl: pass long values where expected

• -: ------------ > 5: 718faf7 gvfs-helper: pass long values where expected

Obviously, we also needed to address some calls in gvfs-helper, which means that the tip commit of this PR branch is not a backport.