Keep bool fields together in context struct defn

Based on feedback from PR:

> Putting all the bool fields consecutively at the
end avoids padding bytes in the middle of the struct
that the compiler will add to maintain the alignment
requirements of the bigger slice fields.

log/log.go

@@ -133,9 +133,8 @@ func WithSuffix(logger Logger, keyvals ...interface{}) Logger {
 type context struct {
 	logger     Logger
 	keyvals    []interface{}
+	sKeyvals   []interface{} // suffixes
 	hasValuer  bool
-	// suffixes
-	sKeyvals   []interface{}
 	sHasValuer bool
 }