title: Include header directory automatically Automake
body: <p>I have an Automake project which has the following directory structure:</p>
  
  <pre><code>Makefile.am
  src/
  src/common
  src/common/common.c
  src/common/common.h
  src/common/Makefile.am
  src/mylib
  src/mylib/mylib.c
  src/mylib/mylib.h
  src/mylib/Makefile.am
  </code></pre>
  
  <p>On <code>src/common/Makefile.am</code> there is a  Libtool convenience library target:</p>
  
  <pre><code>noinst_LTLIBRARIES = libcommon.la
  libcommon_la_SOURCES = common.c common.h
  </code></pre>
  
  <p>On <code>src/mylib/Makefile.am</code> there is a Libtool public shared library target:             </p>
  
  <pre><code>lib_LTLIBRARIES = libmylib.la
  libmylib_la_SOURCES = mylib.c mylib.h
  libmylib_la_LIBADD = ../common/libcommon.la
  </code></pre>
  
  <p>Now I expected Automake to be smart enough to automatically add to  <code>libmylib_la_CFLAGS</code> the <code>-I</code> pointing to the directory where <code>common.h</code> is, since it depends on <code>libcommon.la</code>.</p>
  
  <p>Is there actually a mechanism to either enable this (similar to CMake's <code>INTERFACE_INCLUDE_DIRECTORIES</code>) or maybe a variable (e.g. <code>libcommon_la_HEADERS</code>) that already contains all headers belonging from <code>libcommon</code> convenience library ?</p>
  
  <p>I have researched everywhere and could not find a way to it instead of adding <code>-I ../common/</code> directly to mylib CFLAGS.</p>