build: separate compiler and libs

compiler/internal/build/overlay.go

@@ -0,0 +1,17 @@
+package build
+
+import (
+	_ "embed"
+)
+
+//go:embed _overlay/go/parser/resolver.go
+var go_parser_resolver string
+
+//go:embed _overlay/net/textproto/textproto.go
+var net_textproto string
+
+var overlayFiles = map[string]string{
+	"math/exp_amd64.go":          "package math;",
+	"go/parser/resolver.go":      go_parser_resolver,
+	"net/textproto/textproto.go": net_textproto,
+}