Fix strict-prototypes warnings

Author: petk

cmake/cmake/modules/FindCclient.cmake

@@ -87,7 +87,7 @@ function(cclient_check_symbol symbol result)
 
       void ${symbol}(void);
       void (*f)(void);
-      char foobar() {
+      char foobar(void) {
         f = ${symbol};
       }
 

cmake/ext/gd/CMakeLists.txt

@@ -374,7 +374,7 @@ if(NOT EXT_GD_EXTERNAL)
             return '\0';
           }
 
-          char foobar();
+          char foobar(void);
 
           int main(void) {
             foobar();