title: Ignore [clang-diagnostic-error] clang-tidy caused by 3rd party headers
body: <p>I am using clang-tidy as a "linter" tool in development. I started to integrate 3rd party software into my code and when I include their header files using:</p>
  
  <pre><code>-I/path/to/include 
  </code></pre>
  
  <p>tons of errors are generated, I haven't even <code>#include</code> the headers yet.</p>
  
  <pre><code>error: too many errors emitted, stopping now [clang-diagnostic-error]
  ...
  /path/to/include/wchar.h:81:1: error: unknown type name 'wint_t' [clang-diagnostic-error]
  wint_t fgetwc(FILE *__stream);
  ^
  /path/to/include/wchar.h:81:15: error: unknown type name 'FILE' [clang-diagnostic-error]
  wint_t fgetwc(FILE *__stream);
                ^
  ...
  </code></pre>
  
  <p>I compile my program using:</p>
  
  <pre><code>/usr/bin/clang-tidy-4.0 /path/to/main.cpp -checks=-*,cppcoreguidelines* -- -lang-c++ -I/path/to/include -std=gnu++11 -Wall -Werror -O0 -g -D&lt;define variables&gt;
  </code></pre>
  
  <p>It seems that these "clang-diagnostic-errors" do not stop compilation, as it continues to compile and runs fine. Is there a flag to turn this error off/suppress it? I do not want to see it since I did not write these header files.</p>
  
  <p>If I get rid of the argument <code>-I/path/to/include</code> everything compiles fine with no errors.</p>