Hide some additional includes.

clients/c/cosmopolite-int.h

@@ -1,6 +1,12 @@
 #ifndef _COSMOPOLITE_INT_H
 #define _COSMOPOLITE_INT_H
 
+#include <curl/curl.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <time.h>
+
 // Declarations that aren't in the public API but are available to the test suite.
 
 struct cosmo_command {

clients/c/cosmopolite.h

@@ -1,12 +1,7 @@
 #ifndef _COSMOPOLITE_H
 #define _COSMOPOLITE_H
 
-#include <curl/curl.h>
 #include <jansson.h>
-#include <pthread.h>
-#include <stdbool.h>
-#include <stdint.h>
-#include <time.h>
 
 #include "promise.h"