Go bindings: Don't import 'fmt' unless it is needed.

mojo/go/BUILD.gn

Index: mojo/go/BUILD.gn
diff --git a/mojo/go/BUILD.gn b/mojo/go/BUILD.gn
index 6fed26a9e06e5de2fe8c0421858e040636519939..5d618c9e6314e805495210af120b976eed1b791c 100644
--- a/mojo/go/BUILD.gn
+++ b/mojo/go/BUILD.gn
@@ -3,6 +3,7 @@
 # found in the LICENSE file.
 
 import("rules.gni")
+import("//mojo/public/tools/bindings/mojom.gni")
 
 go_library("application") {
   sources = [
@@ -85,6 +86,7 @@ if (is_linux) {
     ]
     deps = [
       ":application",
+      ":more_test_mojoms",
       ":platform_cgo",
       "//examples/echo",
       "//mojo/edk/base_edk",
@@ -93,3 +95,13 @@ if (is_linux) {
     ]
   }
 }
+
+# These are additional test mojoms beyond those in the target
+# //mojo/public/interfaces/bindings/tests:test_interfaces.
+# These are built without 'generate_type_info = true' and so
+# allow us to test the go code generation in this mode also.
+mojom("more_test_mojoms") {
+  sources = [
+    "tests/test_enums.mojom",
+  ]
+}