[C++] Add and fix define_newline.mk
diff --git a/parser.cc b/parser.cc
index 3555758..5ce1e8e 100644
--- a/parser.cc
+++ b/parser.cc
@@ -145,14 +145,14 @@
   }
 
   void ParseLine(StringPiece line) {
-    if (line.empty() || (line.size() == 1 && line[0] == '\r'))
-      return;
-
     if (!define_name_.empty()) {
       ParseInsideDefine(line);
       return;
     }
 
+    if (line.empty() || (line.size() == 1 && line[0] == '\r'))
+      return;
+
     current_directive_ = AssignDirective::NONE;
 
     if (line[0] == '\t' && state_ != ParserState::NOT_AFTER_RULE) {