compiler: add support for new language features of Go 1.17

compiler/testdata/go1.17.go

@@ -0,0 +1,41 @@
+package main
+
+// Test changes to the language introduced in Go 1.17.
+// For details, see: https://tip.golang.org/doc/go1.17#language
+// These tests should be merged into the regular slice tests once Go 1.17 is the
+// minimun Go version for TinyGo.
+
+import "unsafe"
+
+func Add32(p unsafe.Pointer, len int) unsafe.Pointer {
+	return unsafe.Add(p, len)
+}
+
+func Add64(p unsafe.Pointer, len int64) unsafe.Pointer {
+	return unsafe.Add(p, len)
+}
+
+func SliceToArray(s []int) *[4]int {
+	return (*[4]int)(s)
+}
+
+func SliceToArrayConst() *[4]int {
+	s := make([]int, 6)
+	return (*[4]int)(s)
+}
+
+func SliceInt(ptr *int, len int) []int {
+	return unsafe.Slice(ptr, len)
+}
+
+func SliceUint16(ptr *byte, len uint16) []byte {
+	return unsafe.Slice(ptr, len)
+}
+
+func SliceUint64(ptr *int, len uint64) []int {
+	return unsafe.Slice(ptr, len)
+}
+
+func SliceInt64(ptr *int, len int64) []int {
+	return unsafe.Slice(ptr, len)
+}