env:fix incorrect extra line breaks & subcmd match

cl/_testlibc/demangle/in.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"github.com/goplus/llgo/c"
+	"github.com/goplus/llgo/cpp/llvm"
+)
+
+func main() {
+	mangledName := "__ZNK9INIReader10ParseErrorEv"
+	if name := llvm.ItaniumDemangle(mangledName, true); name != nil {
+		c.Printf(c.Str("%s\n"), name)
+	} else {
+		println("Failed to demangle")
+	}
+}