gn: Add runtime_link_output to tool("solib")

tools/gn/target.cc

Index: tools/gn/target.cc
diff --git a/tools/gn/target.cc b/tools/gn/target.cc
index 7dd192181ea891e96aa6a9762470fc63af02496e..91b83f73a0d8eac717316a2b4fbc0279917ed9d3 100644
--- a/tools/gn/target.cc
+++ b/tools/gn/target.cc
@@ -513,6 +513,7 @@ void Target::FillOutputFiles() {
     case SHARED_LIBRARY:
       CHECK(tool->outputs().list().size() >= 1);
       check_tool_outputs = true;
+// XXX
       if (tool->link_output().empty() && tool->depend_output().empty()) {
         // Default behavior, use the first output file for both.
         link_output_file_ = dependency_output_file_ =
@@ -531,6 +532,13 @@ void Target::FillOutputFiles() {
                   this, tool, tool->depend_output());
         }
       }
+      if (tool->runtime_link_output().empty()) {
+        runtime_link_output_file_ = link_output_file_;
+      } else {
+          runtime_link_output_file_ =
+              SubstitutionWriter::ApplyPatternToLinkerAsOutputFile(
+                  this, tool, tool->runtime_link_output());
+      }
       break;
     case UNKNOWN:
     default: