Implement runtime functions for reflect

The reflect package isn't supported yet. But at least the Go
parser/typechecker can now deal with it.

src/runtime/gc.go

@@ -28,3 +28,11 @@ func alloc(size uintptr) unsafe.Pointer {
 func free(ptr unsafe.Pointer) {
 	// TODO: use a GC
 }
+
+func GC() {
+	// Unimplemented.
+}
+
+func KeepAlive(x interface{}) {
+	// Unimplemented. Only required with SetFinalizer().
+}

src/runtime/runtime_unix.go

@@ -56,3 +56,11 @@ func alloc(size uintptr) unsafe.Pointer {
 func free(ptr unsafe.Pointer) {
 	//C.free(ptr) // TODO
 }
+
+func GC() {
+	// Unimplemented.
+}
+
+func KeepAlive(x interface{}) {
+	// Unimplemented. Only required with SetFinalizer().
+}

src/runtime/stack.go

@@ -0,0 +1,16 @@
+package runtime
+
+type Func struct {
+}
+
+func FuncForPC(pc uintptr) *Func {
+	return nil
+}
+
+func (f *Func) Name() string {
+	return ""
+}
+
+func Caller(skip int) (pc uintptr, file string, line int, ok bool) {
+	return 0, "", 0, false
+}