small skia_shared_lib=1 build fix for cross-process picture demo

gyp/nanomsg.gyp

 {
   'variables': {
     'skia_warnings_as_errors': 0,
   },
   'targets': [{
     # Draws pictures cross-process.
     'target_name': 'nanomsg_picture_demo',
     'type': 'executable',
     'dependencies': [
       'skia_lib.gyp:skia_lib',
@@ skipping 97 matching lines @@
       '../third_party/externals/nanomsg/src/utils/stopwatch.c',
       '../third_party/externals/nanomsg/src/utils/thread.c',
       '../third_party/externals/nanomsg/src/utils/wire.c',
     ],
 
     # TODO(mtklein): Support Windows?
     # To refresh: cd third_party/externals/nanomsg; ./autogen.sh; ./configure; copy from Makefile.
     'conditions': [
       ['skia_os == "linux"', {
         'cflags': [ '-Wno-missing-field-initializers' ],
-        'libraries': [ '-lanl' ],       # Provides getaddrinfo_a and co.
+        'libraries': [
+            '-lpthread',
+            '-lanl',  # Provides getaddrinfo_a and co.
+        ],
         'direct_dependent_settings': {
-            'libraries': [ '-lanl' ],
+            'libraries': [ '-lpthread', '-lanl' ],
         },
         'defines=': [             # equals sign throws away most Skia defines (just noise)
           'HAVE_ACCEPT4',
           'HAVE_ARPA_INET_H',
           'HAVE_CLOCK_GETTIME',
           'HAVE_DLFCN_H',
           'HAVE_EPOLL_CREATE',
           'HAVE_EVENTFD',
           'HAVE_GETIFADDRS',
           'HAVE_INTTYPES_H',
@@ skipping 64 matching lines @@
           'NN_USE_IFADDRS',
           'NN_USE_KQUEUE',
           'NN_USE_PIPE',
           'STDC_HEADERS',
           '_THREAD_SAFE',
         ],
       }],
     ]
   }]
 }