title: Make include in makefiles be relative to the file's location
body: <p>Directly related to <a href="https://stackoverflow.com/questions/8071248/make-within-ndk-gdb-chokes-on-relative-path-in-android-mk">this question</a>. How can I make the <code>include</code> directive in makefiles behave relatively to the location of the current script?</p>
  
  <p>Assume that the <strong>current</strong> path is arbitrary and you have no control over it. Only the makefile location is known. Your makefile is not the root one - it's included. That's exactly how it is in Android NDK.</p>
  
  <p>Is there a builtin variable with the current makefile's name? Can I strip filename away from it, leaving just the path? Using make 3.81 on Cygwin.</p>