title: there are error that 'xxx/xxx.h' file not found when pod lib lint
body: <p>it is a simple spec that is</p>
  
  <pre><code>#
  # Be sure to run `pod lib lint test.podspec' to ensure this is a
  # valid spec before submitting.
  #
  # Any lines starting with a # are optional, but their use is encouraged
  # To learn more about a Podspec see http://guides.cocoapods.org/syntax/podspec.html
  #
  
  Pod::Spec.new do |s|
    s.name             = 'test'
    s.version          = '0.1.0'
    s.summary          = 'A short description of test.'
  
  # This description is used to generate tags and improve search results.
  #   * Think: What does it do? Why did you write it? What is the focus?
  #   * Try to keep it short, snappy and to the point.
  #   * Write the description between the DESC delimiters below.
  #   * Finally, don't worry about the indent, CocoaPods strips it!
  
    s.description      = &lt;&lt;-DESC
  TODO: Add long description of the pod here.
                     DESC
  
    s.homepage         = 'https://github.com/vincentgemini/test'
    # s.screenshots     = 'www.example.com/screenshots_1', 'www.example.com/screenshots_2'
    s.license          = { :type =&gt; 'MIT', :file =&gt; 'LICENSE' }
    s.author           = { 'vincentgemini' =&gt; 'vincent_gemini@163.com' }
    s.source           = { :git =&gt; 'https://github.com/vincentgemini/test.git', :tag =&gt; s.version.to_s }
    # s.social_media_url = 'https://twitter.com/&lt;TWITTER_USERNAME&gt;'
  
    s.ios.deployment_target = '8.0'
  
    s.source_files = 'test/Classes/**/*'
    s.vendored_libraries = 'test/Module/**/*.a' 
  
    # s.resource_bundles = {
    #   'test' =&gt; ['test/Assets/*.png']
    # }
  
    # s.public_header_files = 'Pod/Classes/**/*.h'
    # s.frameworks = 'UIKit', 'MapKit'
    # s.dependency 'AFNetworking', '~&gt; 2.3'
  end
  </code></pre>
  
  <p>the folder tree is</p>
  
  <pre><code>test
  ├── Assets
  ├── Classes
  │   ├── ViewController.h
  │   └── ViewController.m
  └── Module
      ├── include
      │   └── MMM
      │       └── MMM.h
      └── libMMM.a
  </code></pre>
  
  <p>but when pod lib lint, there is a error that /Users/gemini_mxz/Desktop/test/test/Classes/ViewController.m:11:9: fatal error: 'MMM/MMM.h' file not found.</p>
  
  <p>the ViewController.m is </p>
  
  <pre><code>- (void)viewDidLoad {
      [super viewDidLoad];
      // Do any additional setup after loading the view, typically from a nib.
  
      MMM *m = [[MMM alloc] init];
      NSLog(@"%@", a);
  }
  </code></pre>
  
  <p>i have try that used preserve_paths or xcconfig, but the error still exist。</p>