Fix the testonly flag for gn ls

This fixes a problem where running 'gn ls' with '--testonly=true' would
not filter out targets who did not have testonly set to true in their
BUILD.gn file.

Bug: 288
Change-Id: I65a5f72d459a0f90fdac58249b5a1661edb66525
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/14680
Reviewed-by: Brett Wilson <brettw@chromium.org>
Commit-Queue: Brett Wilson <brettw@chromium.org>

src/gn/commands.cc

diff --git a/src/gn/commands.cc b/src/gn/commands.cc
index 02926ec..f81f7ab 100644
--- a/src/gn/commands.cc
+++ b/src/gn/commands.cc
@@ -469,9 +469,9 @@
   if (cmdline.HasSwitch(testonly_switch)) {
     std::string value = cmdline.GetSwitchValueString(testonly_switch);
     if (value == "true") {
-      testonly_mode_ = TESTONLY_TRUE;
+      result.testonly_mode_ = TESTONLY_TRUE;
     } else if (value == "false") {
-      testonly_mode_ = TESTONLY_FALSE;
+      result.testonly_mode_ = TESTONLY_FALSE;
     } else {
       Err(Location(), "Bad value for --testonly.",
           "I was expecting --testonly=true or --testonly=false.")