Add Makefile and test programs

rt/Makefile

+CXX=g++-11
+CXXFLAGS=-g -O3 -fwhole-program -flto -Wall -Wextra -Werror -std=c++20 -fcoroutines -I.
+LDLIBS=-ljemalloc

rt/loop.cpp

+#include <task.hpp>
+
+#include <cstdio>
+
+using namespace typon;
+
+task<int> add(int a, int b) {
+  co_return a + b;
+}
+
+task<int> loop(int n) {
+  int result = 0;
+  for (int i = 0; i < n; i++) {
+    result = result + co_await add(i, i+1);
+  }
+  co_return result;
+}
+
+int main() {
+  int result = loop(100000000).call();
+
+  printf("%d\n", result);
+}

rt/main.cpp

+#include <task.hpp>
+
+#include <cstdio>
+
+using namespace typon;
+
+task<int> fibo(int n) {
+  if (n < 2) {
+    co_return n;
+  }
+  int a = co_await fibo(n - 1);
+  int b = co_await fibo(n - 2);
+  co_return a + b;
+}
+
+int main() {
+  int result = fibo(40).call();
+  printf("%d\n", result);
+}