guile-lib: fix module installation in the output

This should now make Guile recognize it as one of the module in its
search path.

pkgs/development/guile-modules/guile-lib/default.nix

@@ -1,6 +1,7 @@
 { lib
 , stdenv
 , fetchurl
+, autoreconfHook
 , guile
 , pkg-config
 , texinfo
@@ -16,6 +17,7 @@ stdenv.mkDerivation rec {
   };
 
   nativeBuildInputs = [
+    autoreconfHook
     pkg-config
   ];
   buildInputs = [
@@ -23,6 +25,12 @@ stdenv.mkDerivation rec {
     texinfo
   ];
 
+  postPatch = ''
+    substituteInPlace configure.ac \
+      --replace 'SITEDIR="$datadir/guile-lib"' 'SITEDIR=$datadir/guile/site/$GUILE_EFFECTIVE_VERSION' \
+      --replace 'SITECCACHEDIR="$libdir/guile-lib/guile/$GUILE_EFFECTIVE_VERSION/site-ccache"' 'SITECCACHEDIR="$libdir/guile/$GUILE_EFFECTIVE_VERSION/site-ccache"'
+  '';
+
   makeFlags = [ "GUILE_AUTO_COMPILE=0" ];
 
   doCheck = !stdenv.isDarwin;