title: flycheck header file not found, but makefile is correct
body: <p>I'm using emacs with flycheck to check C source code syntax and trying to get it working with glib. My code compiles and runs correctly, however flycheck reports a file not found error in the <code>#include &lt;glib.h&gt;</code> line and stops reporting further errors, defeating its purpose.</p>
  
  <p>Here's my sample source file:</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;glib.h&gt;
  
  GList* list = NULL;
  
  int main() {
      list = g_list_append(list, "a");
      list = g_list_append(list, "b");
      list = g_list_append(list, "c");
  
      for ( ; list!=NULL; list=list-&gt;next) {
          printf("%s\n", (char*)list-&gt;data);
      }
      return 0;
  }
  </code></pre>
  
  <p>And the makefile</p>
  
  <pre><code>P=glist
  OBJECTS=
  CFLAGS=-g -Wall -O3 `pkg-config --cflags glib-2.0`
  LDLIBS=`pkg-config --libs glib-2.0`
  CC=gcc-4.9
  
  $(P): $(OBJECTS)
  </code></pre>
  
  <p>If I change the include line to read <code>#include &lt;glib-2.0/glib.h&gt;</code> I get the following error reported in the minibuffer:</p>
  
  <blockquote>
    <p>Checker c/c++-clang returned non-zero exit code 1, but no errors from
    output: In file included from
    /var/folders/<em>f/ts3</em><strong>zs3cjbq1fqfhdfrl1w0000gn/T/flycheck87881gVK/glist.c:2:
    /usr/local/include/glib-2.0/glib.h:32:10: error: 'glib/galloca.h' file
    not found with  include; use "quotes" instead In file included
    from
    /var/folders/_f/ts3</strong>_zs3cjbq1fqfhdfrl1w0000gn/T/flycheck87881gVK/glist.c:2:
    In file included from /usr/local/include/glib-2.0/glib.h:32:
    /usr/local/include/glib-2.0/glib/galloca.h:34:10: fatal error:
    'glib/gtypes.h' file not found</p>
    
    <p>Checker definition probably flawed.</p>
  </blockquote>
  
  <p>Still the code compiles and runs correctly. I'm not sure why it can't find <code>glib/gtypes.h</code> as it exists under one of the included directories. The output from <code>pkg-config --cflags glib-2.0</code> is:</p>
  
  <blockquote>
    <p>-I/usr/local/Cellar/glib/2.36.4/include/glib-2.0 -I/usr/local/Cellar/glib/2.36.4/lib/glib-2.0/include -I/usr/local/opt/gettext/include </p>
  </blockquote>
  
  <p>Listing <code>ls /usr/local/Cellar/glib/2.36.4/include/glib-2.0/glib/gtypes.h</code></p>
  
  <blockquote>
    <p>/usr/local/Cellar/glib/2.36.4/include/glib-2.0/glib/gtypes.h</p>
  </blockquote>
  
  <p>And listing <code>ls /usr/local/include/glib-2.0/glib/gtypes.h</code></p>
  
  <blockquote>
    <p>/usr/local/include/glib-2.0/glib/gtypes.h</p>
  </blockquote>
  
  <p>So the file is there. I wouldn't mind switching to flymake if flycheck is to blame, but I'm not sure if it's a problem with my setup or flycheck itself. Plus flycheck configuration is dead simple and otherwise works very well. I'm using version 20130904.2245 installed from elpa.</p>