meta: move photon/libc to root

libc/stdlib/atexit.c

@@ -0,0 +1,21 @@
+#define MAX_FN 32
+
+static void(*atexit_fn[MAX_FN])(void);
+static int atexit_fn_count = 0;
+
+int atexit(void(*fn)(void))
+{
+    if (atexit_fn_count == MAX_FN) {
+        return -1;
+    }
+
+    atexit_fn[atexit_fn_count++] = fn;
+    return 0;
+}
+
+void __crt_run_atexit()
+{
+    for (int i = 0; i < atexit_fn_count; i++) {
+        atexit_fn[i]();
+    }
+}