add c skeleton

kernel/memory/pageframealloc.cc

@@ -0,0 +1,19 @@
+#include "../memory/pageframealloc.h"
+#include <cstdint>
+#include "pageframe.h"
+
+void PageFrameAllocator::init(){
+}
+
+void PageFrameAllocator::stats(){
+}
+
+PageFrame* PageFrameAllocator::alloc(bool kernel){
+    return 0;
+}
+
+void PageFrameAllocator::free(PageFrame* frame){
+}
+
+void PageFrameAllocator::free(uintptr_t addr){
+}