Basic underpinnings of the gyp equivalent of the Linux SHARED=1 build:...

third_party/modp_b64/modp_b64.gyp

 # Copyright (c) 2009 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'includes': [
     '../../build/common.gypi',
   ],
   'targets': [
     {
       'target_name': 'modp_b64',
-      'type': 'static_library',
+      'type': '<(library)',
       'msvs_guid': '7100F41F-868D-4E99-80A2-AF8E6574749D',
       'sources': [
         'modp_b64.cc',
         'modp_b64.h',
         'modp_b64_data.h',
       ],
       'include_dirs': [
         '../..',
       ],
     },
   ],
 }