title: why does `make` using _CoqProject in coqide differ from `coqc` on the commandline?
body: <p>I have two short files: cc_test is given by 
  <code>Lemma cc: 4 = 4. Proof. auto. Qed.</code>
  and libtest is given by 
  <code>Require Import cc_test.  Check cc.</code></p>
  
  <p>When I execute 
  <code>coqc -R . ClosureLib -top ClosureLib cc_test</code> 
  in directory "/home/barry/svn/Coq/Closure_Calculus" 
  and 
  <code>coqc -R "/home/barry/svn/Coq/Closure_Calculus" ClosureLib libtest</code>
  in its directory, I get the expected output 
  <code>cc: 4 = 4</code> </p>
  
  <p>However, when the arguments to coqc above (from -R to the end) are placed in _CoqProject files, and I call <code>Make makefile</code> and then <code>Make</code> from the coqide menu, cc_test is okay but libtest yields output 
  <code>File "./libtest.v", line 1, characters 15-22:
  Error: Unable to locate library cc_test.</code></p>
  
  <p>How should I modify the project files to make this work? </p>
  
  <p>Comment: the coq reference manual (Chapter 15) does not mention any differences between these approaches. Also, the argument "-top ClosureLib" 
  seems to be necessary in the commandline approach, but does not appear to matter using <code>make</code> as, in other experiments, I frequently get error messages saying that it found Top.foo but not ClosureLib.foo.</p>