Fix a bug with mojom imports where 2 imports with the same namespace would

mojo/mojo_public.gypi

 {
   'targets': [
     {
       'target_name': 'mojo_system',
       'type': 'shared_library',
       'defines': [
         'MOJO_SYSTEM_IMPLEMENTATION',
       ],
       'include_dirs': [
         '..',
@@ skipping 180 matching lines @@
         'public/bindings/lib/scratch_buffer.h',
         'public/bindings/lib/sync_dispatcher.cc',
       ],
     },
     {
       'target_name': 'mojo_sample_service',
       'type': 'static_library',
       'sources': [
         'public/bindings/tests/sample_service.mojom',
         'public/bindings/tests/sample_import.mojom',
+        'public/bindings/tests/sample_import2.mojom',
       ],
       'includes': [ 'public/bindings/mojom_bindings_generator.gypi' ],
       'export_dependent_settings': [
         'mojo_bindings',
         'mojo_system',
       ],
     },
     {
       'target_name': 'mojo_environment_standalone',
       'type': 'static_library',
@@ skipping 34 matching lines @@
         'public/shell/service.h',
       ],
       'includes': [ 'public/bindings/mojom_bindings_generator.gypi' ],
       'export_dependent_settings': [
         'mojo_bindings',
         'mojo_system',
       ],
     },
   ],
 }