[Error Messages] Add toolchain to output collission error

Add the toolchain to the printed out GN label for each target that's
creating the output file collision.

Change-Id: I202c3f295065397f009a73cd32c0be0f12dc23bd
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/11780
Commit-Queue: Petr Hosek <phosek@google.com>
Reviewed-by: Petr Hosek <phosek@google.com>

src/gn/ninja_build_writer.cc

diff --git a/src/gn/ninja_build_writer.cc b/src/gn/ninja_build_writer.cc
index 9fb6a7d..908c5df 100644
--- a/src/gn/ninja_build_writer.cc
+++ b/src/gn/ninja_build_writer.cc
@@ -156,7 +156,7 @@
   DCHECK(matches.size() >= 2);
   std::string matches_string;
   for (const Target* target : matches)
-    matches_string += "  " + target->label().GetUserVisibleName(false) + "\n";
+    matches_string += "  " + target->label().GetUserVisibleName(true) + "\n";
 
   Err result(matches[0]->defined_from(), "Duplicate output file.",
              "Two or more targets generate the same output:\n  " +

src/gn/ninja_build_writer_unittest.cc

diff --git a/src/gn/ninja_build_writer_unittest.cc b/src/gn/ninja_build_writer_unittest.cc
index 8bc6839..fab082f 100644
--- a/src/gn/ninja_build_writer_unittest.cc
+++ b/src/gn/ninja_build_writer_unittest.cc
@@ -248,8 +248,8 @@
       "setting an output_name on one of them.\n"
       "\n"
       "Collisions:\n"
-      "  //foo:bar\n"
-      "  //bar:bar\n";
+      "  //foo:bar()\n"
+      "  //bar:bar()\n";
 
   EXPECT_EQ(expected_help_test, err.help_text());
 }