Enhance GN introspection

tools/gn/label_pattern.h

Index: tools/gn/label_pattern.h
diff --git a/tools/gn/label_pattern.h b/tools/gn/label_pattern.h
index e805ffb62ef60dc82419f4baf6dbd9528ed6923b..5c032603ee8d90d5edf79972c9c3210bca087478 100644
--- a/tools/gn/label_pattern.h
+++ b/tools/gn/label_pattern.h
@@ -39,6 +39,9 @@ class LabelPattern {
                                  const Value& value,
                                  Err* err);
 
+  // Returns true if the given input string might match more than one thing.
+  static bool HasWildcard(const std::string& str);
+
   // Returns true if this pattern matches the given label.
   bool Matches(const Label& label) const;