[C++] Fix multiline_recipe.mk
diff --git a/strutil.h b/strutil.h
index 7bda9d1..8ab2667 100644
--- a/strutil.h
+++ b/strutil.h
@@ -125,4 +125,6 @@
 size_t FindOutsideParen(StringPiece s, char c);
 size_t FindTwoOutsideParen(StringPiece s, char c1, char c2);
 
+size_t FindEndOfLine(StringPiece s, size_t e, size_t* lf_cnt);
+
 #endif  // STRUTIL_H_