title: Add custom module to Target build settings in Podspec
body: <p>I try to add a custom module into my Podspec, but setting:
  <code>module_map : 'module/module.modulemap'</code></p>
  
  <p>and in the build settings:</p>
  
  <pre><code>xcconfig = { 'MODULEMAP_FILE' =&gt; '$(SRCROOT)/module', 'HEADER_SEARCH_PATHS' =&gt; '$(SDKROOT)/usr/include/libxml2 $(PODS_ROOT)/module $(SDKROOT)/usr/include/libresolv',
  'LIBRARY_SEARCH_PATHS' =&gt; '"$(PODS_ROOT)/XMPPFramework/Vendor/libidn"', 'OTHER_LDFLAGS' =&gt; '"-lxml2"', 'CLANG_ALLOW_NON_MODULAR_INCLUDES_IN_FRAMEWORK_MODULES' =&gt; 'YES', 'ENABLE_BITCODE' =&gt; 'NO',  'SWIFT_INCLUDE_PATHS' =&gt; '$(SRCROOT)/module/module.modulemap'}
  </code></pre>
  
  <p>But pod spec lint will fail, telling me that he doesn't know my custom module.</p>