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

third_party/bzip2/bzip2.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': 'bzip2',
-      'type': 'static_library',
+      'type': '<(library)',
       'defines': ['BZ_NO_STDIO'],
       'msvs_guid': '2A70CBF0-847E-4E3A-B926-542A656DC7FE',
       'sources': [
         'blocksort.c',
         'bzlib.c',
         'bzlib.h',
         'bzlib_private.h',
         'compress.c',
         'crctable.c',
         'decompress.c',
         'huffman.c',
         'randtable.c',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           '.',
         ],
       },
       'conditions': [
         ['OS=="win"', {
           'product_name': 'libbzip2',
         }, {  # else: OS!="win"
           'product_name': 'bz2',
         }],
       ],
     },
   ],
 }