Merge pull request commonmark#310 from huven/prototype-warning

Fix strict prototype clang warning

Author: kevinbackhouse

src/node.c

@@ -39,7 +39,7 @@ void cmark_register_node_flag(cmark_node_internal_flags *flags) {
   nextflag <<= 1;
 }
 
-void cmark_init_standard_node_flags() {}
+void cmark_init_standard_node_flags(void) {}
 
 bool cmark_node_can_contain_type(cmark_node *node, cmark_node_type child_type) {
   if (child_type == CMARK_NODE_DOCUMENT) {

src/node.h

@@ -128,7 +128,7 @@ void cmark_register_node_flag(cmark_node_internal_flags *flags);
  * library. It is now a no-op.
  */
 CMARK_GFM_EXPORT
-void cmark_init_standard_node_flags();
+void cmark_init_standard_node_flags(void);
 
 static CMARK_INLINE cmark_mem *cmark_node_mem(cmark_node *node) {
   return node->content.mem;