reflect: add reflect.TypeOf

This is the beginning of true reflection support in TinyGo.

src/reflect/value.go

@@ -1,24 +1,21 @@
 package reflect
 
 import (
-	_ "unsafe" // for go:linkname
+	"unsafe"
 )
 
 // This is the same thing as an interface{}.
 type Value struct {
 	typecode Type
-	value    *uint8
+	value    unsafe.Pointer
 }
 
 func Indirect(v Value) Value {
 	return v
 }
 
-func ValueOf(i interface{}) Value
-
-//go:linkname _ValueOf reflect.ValueOf
-func _ValueOf(i Value) Value {
-	return i
+func ValueOf(i interface{}) Value {
+	return *(*Value)(unsafe.Pointer(&i))
 }
 
 func (v Value) Interface() interface{}

src/runtime/interface.go

@@ -5,9 +5,11 @@ package runtime
 // Interfaces are represented as a pair of {typecode, value}, where value can be
 // anything (including non-pointers).
 
+import "unsafe"
+
 type _interface struct {
 	typecode uintptr
-	value    *uint8
+	value    unsafe.Pointer
 }
 
 // Return true iff both interfaces are equal.