title: File path issue with Meson and Eigen
body: <p>I cannot make local include paths work in the Meson build system.</p>
  
  <p>This C++ inclusion works correctly:</p>
  
  <pre><code>#include &lt;/cygdrive/c/Users/user/project/Third-Party/eigen/Eigen/Dense&gt;
  </code></pre>
  
  <p>This one does not:</p>
  
  <pre><code>#include "Third-Party/eigen/Eigen/Dense"
  </code></pre>
  
  <blockquote>
    <p>fatal error: Eigen/Dense: No such file or directory</p>
  </blockquote>
  
  <p>In the Meson build file, I tried to add Eigen's path, without success:</p>
  
  <pre><code># '.' will refer to current build directory
  include_dirs = include_directories('include', '.', '../project/Third-Party/eigen')
  </code></pre>
  
  <p>This is the project tree structure:</p>
  
  <pre><code>project
     meson.build
     src
        meson.build
        example.h
        example.cpp
     Third-Party
        eigen  (headers only lib)
           Eigen
  </code></pre>
  
  <p>Note: with CMake I do not have this issue.</p>