implement clipboard on iOS

src/util.cpp

@@ -610,24 +610,6 @@ std::string str_replace(const std::string& string, const std::string& search, co
     return ret;
 }
 
-std::string clipboard_get_text()
-{
-#if _WIN32
-    extern std::string win32_clipboard_get_text();
-    return win32_clipboard_get_text();
-#elif _IOS_
-#endif
-}
-
-bool clipboard_set_text(const std::string& s)
-{
-#if _WIN32
-    extern bool win32_clipboard_set_text(const std::string & s);
-    return win32_clipboard_set_text(s);
-#elif _IOS_
-#endif
-}
-
 static const char* gl2str(GLenum err)
 {
     switch (err)