Add nanomsg to third_party, with some demos.

gyp/most.gyp

 # Build ALMOST everything provided by Skia; this should be the default target.
 #
 # This omits the following targets that many developers won't want to build:
 # - debugger: this requires QT to build
 #
 {
   'variables': {
     'skia_skip_gui%': 0,
   },
   'targets': [
@@ skipping 13 matching lines @@
 #       'pdfviewer.gyp:pdfviewer',
         'dm.gyp:dm',
       ],
       'conditions': [
         ['skia_os == "android"', {
           'dependencies': [ 'android_system.gyp:SampleApp_APK' ],
         }],
         ['skia_os == "ios"', {
           'dependencies!': [ 'SampleApp.gyp:SampleApp' ],
         }],
+        ['skia_os == "mac" or skia_os == "linux"', {
+          'dependencies': [ 'nanomsg.gyp:*' ],
+        }],
         [ 'skia_skip_gui',
           {
             'dependencies!': [
               'SampleApp.gyp:SampleApp',
             ]
           }
         ]
       ],
     },
   ],
 }