reflect: implement MakeChan

TinyGo had MakeMap/MakeSlice but not MakeChan. Implement it via the runtime
chanMake primitive (mirroring MakeMap), so packages that call reflect.MakeChan
(e.g. github.com/ugorji/go/codec used by gin) compile and work.

src/internal/reflectlite/value.go

@@ -2208,6 +2208,9 @@ func hashmapMake(keySize, valueSize uintptr, sizeHint uintptr, alg uint8) unsafe
 //go:linkname hashmapMakeReflect runtime.hashmapMakeReflect
 func hashmapMakeReflect(keySize, valueSize, sizeHint uintptr, keyType unsafe.Pointer) unsafe.Pointer
 
+//go:linkname chanMake runtime.chanMake
+func chanMake(elementSize uintptr, bufSize uintptr) unsafe.Pointer
+
 // MakeMapWithSize creates a new map with the specified type and initial space
 // for approximately n elements.
 func MakeMapWithSize(typ Type, n int) Value {
@@ -2254,6 +2257,26 @@ func MakeMap(typ Type) Value {
 	return MakeMapWithSize(typ, 8)
 }
 
+// MakeChan creates a new channel with the specified type and buffer size.
+func MakeChan(typ Type, size int) Value {
+	if typ.Kind() != Chan {
+		panic(&ValueError{Method: "MakeChan", Kind: typ.Kind()})
+	}
+	if size < 0 {
+		panic("reflect.MakeChan: negative buffer size")
+	}
+	if typ.(*RawType).ChanDir() != BothDir {
+		panic("reflect.MakeChan: unidirectional channel type")
+	}
+	elem := typ.Elem().(*RawType)
+	ch := chanMake(elem.Size(), uintptr(size))
+	return Value{
+		typecode: typ.(*RawType),
+		value:    ch,
+		flags:    valueFlagExported,
+	}
+}
+
 func (v Value) Call(in []Value) []Value {
 	panic("unimplemented: (reflect.Value).Call()")
 }