gn format: Add 'outputs' to preferred-multiline lists

tools/gn/format_test_data/042.golden

Index: tools/gn/format_test_data/042.golden
diff --git a/tools/gn/format_test_data/042.golden b/tools/gn/format_test_data/042.golden
index 983cec2bc3936f98dc5de4236d80cc42009f65f5..1968d0acd94f7c846fc4e70e074c777c3762bb65 100644
--- a/tools/gn/format_test_data/042.golden
+++ b/tools/gn/format_test_data/042.golden
@@ -10,6 +10,7 @@ if (true) {
   include_dirs = []
   inputs = []
   ldflags = []
+  outputs = []
   public_deps = []
   sources = []
 } else if (true) {
@@ -31,6 +32,9 @@ if (true) {
     "x",
   ]
   ldflags = [ "x" ]
+  outputs = [
+    "x",
+  ]
   public_deps = [
     "x",
   ]
@@ -88,6 +92,11 @@ if (true) {
     "y",
     "z",
   ]
+  outputs = [
+    "x",
+    "y",
+    "z",
+  ]
   public_deps = [
     "x",
     "y",