restructure project

kernels/hello/hello.c

@@ -0,0 +1,13 @@
+#include <am.h>
+#include <klib-macros.h>
+
+int main(const char *args) {
+  const char *fmt =
+    "Hello, AbstractMachine!\n"
+    "mainargs = '%'.\n";
+
+  for (const char *p = fmt; *p; p++) {
+    (*p == '%') ? putstr(args) : putch(*p);
+  }
+  return 0;
+}