tidy-up: drop stray casts for allocated pointers

Closes #21865

docs/FAQ.md

@@ -1017,7 +1017,7 @@ WriteMemoryCallback(void *ptr, size_t size, size_t nmemb, void *data)
   size_t realsize = size * nmemb;
   struct MemoryStruct *mem = (struct MemoryStruct *)data;
 
-  mem->memory = (char *)realloc(mem->memory, mem->size + realsize + 1);
+  mem->memory = realloc(mem->memory, mem->size + realsize + 1);
   if(mem->memory) {
     memcpy(&(mem->memory[mem->size]), ptr, realsize);
     mem->size += realsize;

docs/examples/multi-event.c

@@ -99,9 +99,7 @@ static void curl_perform(int fd, short event, void *arg)
 
 static struct curl_context *create_curl_context(curl_socket_t sockfd)
 {
-  struct curl_context *context;
-
-  context = (struct curl_context *)malloc(sizeof(*context));
+  struct curl_context *context = malloc(sizeof(*context));
 
   context->sockfd = sockfd;
 

docs/examples/multi-uv.c

@@ -58,9 +58,7 @@ struct curl_context {
 static struct curl_context *create_curl_context(curl_socket_t sockfd,
                                                 struct datauv *uv)
 {
-  struct curl_context *context;
-
-  context = (struct curl_context *)malloc(sizeof(*context));
+  struct curl_context *context = malloc(sizeof(*context));
 
   context->sockfd = sockfd;
   context->uv = uv;