gn: Add runtime_link_output to tool("solib")

tools/gn/target.h

Index: tools/gn/target.h
diff --git a/tools/gn/target.h b/tools/gn/target.h
index 18e5fb816dd38470de6df31e409ef312f850b153..f49fdba4c2ab6be3441c79e0541a832caeb17b5b 100644
--- a/tools/gn/target.h
+++ b/tools/gn/target.h
@@ -257,6 +257,9 @@ class Target : public Item {
   const OutputFile& dependency_output_file() const {
     return dependency_output_file_;
   }
+  const OutputFile& runtime_link_output_file() const {
+    return runtime_link_output_file_;
+  }
 
   // Computes the set of output files resulting from compiling the given source
   // file. If the file can be compiled and the tool exists, fills the outputs
@@ -350,6 +353,7 @@ class Target : public Item {
   std::vector<OutputFile> computed_outputs_;
   OutputFile link_output_file_;
   OutputFile dependency_output_file_;
+  OutputFile runtime_link_output_file_;
 
   DISALLOW_COPY_AND_ASSIGN(Target);
 };