fixes to make shared libraries build

templates/vsprojects/vs2013/grpc_csharp_ext_shared.vcxproj.template

 <%namespace file="vcxproj_defs.include" import="gen_project"/>\
-${gen_project('grpc_csharp_ext', libs, targets, configuration_type = 'DynamicLibrary', project_guid = '{C26D04A8-37C6-44C7-B458-906C9FCE928C}')}
+${gen_project('grpc_csharp_ext', libs, targets, configuration_type = 'DynamicLibrary', project_guid = '{C26D04A8-37C6-44C7-B458-906C9FCE928C}', additional_props = ['winsock'])}

templates/vsprojects/vs2013/grpc_shared.vcxproj.template

 <%namespace file="vcxproj_defs.include" import="gen_project"/>\
-${gen_project('grpc', libs, targets, configuration_type = 'DynamicLibrary', project_guid = '{F2EE8FDB-F1E0-43A0-A297-6F255BB52AAA}', additional_props = ['ssl', 'winsock'])}
+${gen_project('grpc', libs, targets, configuration_type = 'DynamicLibrary', project_guid = '{F2EE8FDB-F1E0-43A0-A297-6F255BB52AAA}', additional_props = ['ssl', 'winsock'], depends_on_zlib = True)}

templates/vsprojects/vs2013/vcxproj_defs.include

 <%def name="to_windows_path(path)">${path.replace('/','\\')}</%def>\
 <%def name="get_subsystem(is_library)">${'Windows' if is_library else 'Console'}</%def>\
-<%def name="gen_project(name, libs, targets, configuration_type = 'StaticLibrary', project_guid = None, additional_props = [])">\
+<%def name="gen_project(name, libs, targets, configuration_type = 'StaticLibrary', project_guid = None, additional_props = [], depends_on_zlib = False)">\
 % for project in vsprojects:
   % if project.name == name:
 <?xml version="1.0" encoding="utf-8"?>
@@ -112,6 +112,11 @@
       <Project>${vsproject_dict[dep].vs_project_guid}</Project>
     </ProjectReference>
     % endfor
+    % if depends_on_zlib:
+    <ProjectReference Include="third_party\zlibvc.vcxproj">
+      <Project>{8fd826f8-3739-44e6-8cc8-997122e53b8d}</Project>
+    </ProjectReference>
+    % endif
   </ItemGroup>
   % endif
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />

vsprojects/vs2013/grpc_csharp_ext_shared.vcxproj

@@ -35,10 +35,12 @@
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
     <Import Project="global.props" />
+    <Import Project="winsock.props" />
   </ImportGroup>
   <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
     <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
     <Import Project="global.props" />
+    <Import Project="winsock.props" />
   </ImportGroup>
   <PropertyGroup Label="UserMacros" />
   <PropertyGroup />

vsprojects/vs2013/grpc_shared.vcxproj

@@ -411,6 +411,9 @@
     <ProjectReference Include="gpr.vcxproj">
       <Project>{B23D3D1A-9438-4EDA-BEB6-9A0A03D17792}</Project>
     </ProjectReference>
+    <ProjectReference Include="third_party\zlibvc.vcxproj">
+      <Project>{8fd826f8-3739-44e6-8cc8-997122e53b8d}</Project>
+    </ProjectReference>
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">