title: GNU make issue: "No rule to make target `pjsip.h', needed by `main.o'"
body: <p>I have been working to write my first makefile and after following some tutorials and reading some links on stackoverflow I managed to write the file, what I am doing is</p>
  
  <ul>
  <li>using .a files from the pjsip api, notice the variables <strong>PJSIP, PJLIB_UTIL</strong> and <strong>PJLIB</strong></li>
  <li>define the path to the .h file using the -I option, see the variables <strong>PJSIP_HDR, PJLIB_HDR</strong> and <strong>PJLIB_U_HDR</strong></li>
  </ul>
  
  <p>I get the following error:</p>
  
  <pre><code> make: ***No rule to make target `pjsip.h', needed by `main.o'.  Stop.
  </code></pre>
  
  <p>It believe that it is usefull to mention that I have only 4 <strong>#includes</strong> in my <strong>.cpp</strong> file</p>
  
  <pre><code>#include &lt;iostream&gt;
  #include &lt;pjsip.h&gt;
  #include &lt;pjlib-util.h&gt;
  #include &lt;pjlib.h&gt;
  </code></pre>
  
  <p>The goal is to have a file called <strong>main</strong> which I can excute, I am using <strong>Ubuntu 14.04</strong> . Here is my makefile</p>
  
  <pre><code>CC = g++
  DEBUG = -g
  CFLAGS = -Wall -c $(DEBUG)
  LFLAGS = -Wall $(DEBUG)
  PJSIP = -L/home/ubuntu/pjsip/trunk/pjsip/lib -llibpjsip-simple-x86_64-unknown-linux-gnu.a -llibpjsip-ua-x86_64-unknown-linux-gnu.a -llibpjsip-x86_64-unknown-linux-gnu.a -llibpjsua2-x86_64-unknown-linux-gnu.a -llibpjsua-x86_64-unknown-linux-gnu.a
  PJLIB = -L/home/ubuntu/pjsip/trunk/pjlib/lib -llibpj-x86_64-unknown-linux-gnu.a
  PJLIB_UTIL = -L/home/ubuntu/pjsip/trunk/pjlib-utils/lib -llibpjlib-util-x86_64-unknown-linux-gnu.a
  PJSIP_HDR = -I/home/ubuntu/pjsip/trunk/pjsip/include/
  PJLIB_HDR = -I/home/ubuntu/pjsip/trunk/pjlib/include/
  PJLIB_U_HDR = -I/home/ubuntu/pjsip/trunk/pjlib-utils/include
  
  main: main.o
          $(CC) $(LFLAGS) main.o -o main
  
  main.o: main.cpp pjsip.h pjlib.h pjlib-utils.h
          $(CC) $(CFLAGS) $(PJSIP_HDR) $(PJLIB_HDR) $(PJLIB_U_HDR) main.cpp $(PJSIP) $(PJLIB) $(PJLIB_UTIL)
  
  clean:
           \rm -f *.o
  </code></pre>
  
  <p>Any extra comments that might help me improve my makefile are welcomed</p>
  
  <p>Thanks in advance</p>