python: line_profiler: fix build with Python 3.7

_line_profiler.c has to be regenerated by Cython.

I did not use fetchpatch because this patch does not have a stable source.

pkgs/development/python-modules/line_profiler/default.nix

@@ -16,12 +16,18 @@ buildPythonPackage rec {
     sha256 = "efa66e9e3045aa7cb1dd4bf0106e07dec9f80bc781a993fbaf8162a36c20af5c";
   };
 
+  patches = [ ./python37.patch ];
+
   buildInputs = [ cython ];
 
   propagatedBuildInputs = [ ipython ];
 
   disabled = isPyPy;
 
+  preBuild = ''
+    rm -f _line_profiler.c
+  '';
+
   checkPhase = ''
     ${python.interpreter} -m unittest discover -s tests
   '';
@@ -32,4 +38,4 @@ buildPythonPackage rec {
     license = lib.licenses.bsd3;
     maintainers = with lib.maintainers; [ fridh ];
   };
-}
+}