fix compile error from #2572 (#2600)

Author: thinkerou

internal/bytesconv/bytesconv.go

@@ -5,16 +5,17 @@
 package bytesconv
 
 import (
-	"reflect"
 	"unsafe"
 )
 
 // StringToBytes converts string to byte slice without a memory allocation.
 func StringToBytes(s string) (b []byte) {
-	sh := *(*reflect.StringHeader)(unsafe.Pointer(&s))
-	bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
-	bh.Data, bh.Len, bh.Cap = sh.Data, sh.Len, sh.Len
-	return b
+	return *(*[]byte)(unsafe.Pointer(
+		&struct {
+			string
+			Cap int
+		}{s, len(s)},
+	))
 }
 
 // BytesToString converts byte slice to string without a memory allocation.