Turn more licenses into lib.licenses style

Should eval cleanly, as far as -A tarball tells me.

Relevant: issue #2999, issue #739

pkgs/tools/graphics/dcraw/default.nix

@@ -22,7 +22,7 @@ stdenv.mkDerivation rec {
   meta = {
     homepage = http://www.cybercom.net/~dcoffin/dcraw/;
     description = "Decoder for many camera raw picture formats";
-    license = "free";
+    license = stdenv.lib.licenses.free;
     platforms = with stdenv.lib.platforms; allBut cygwin;
     maintainers = [ stdenv.lib.maintainers.urkud ];
   };

pkgs/tools/graphics/exiftags/default.nix

@@ -19,7 +19,7 @@ stdenv.mkDerivation {
   meta = {
     homepage = http://johnst.org/sw/exiftags/;
     description = "Displays EXIF data from JPEG files";
-    license = "free";
+    license = stdenv.lib.licenses.free;
     maintainers = with stdenv.lib.maintainers; [viric];
   };
 }

pkgs/tools/graphics/jhead/default.nix

@@ -19,7 +19,7 @@ stdenv.mkDerivation {
   meta = {
     homepage = http://www.sentex.net/~mwandel/jhead/;
     description = "Exif Jpeg header manipulation tool";
-    license = "free";
+    license = stdenv.lib.licenses.free;
     maintainers = with stdenv.lib.maintainers; [viric];
   };
 }

pkgs/tools/graphics/pngcrush/default.nix

@@ -17,7 +17,7 @@ stdenv.mkDerivation rec {
   meta = {
     homepage = http://pmt.sourceforge.net/pngcrush;
     description = "A PNG optimizer";
-    license = "free";
+    license = stdenv.lib.licenses.free;
     platforms = with stdenv.lib.platforms; linux;
     maintainers = with stdenv.lib.maintainers; [ the-kenny ];
   };

pkgs/tools/graphics/povray/default.nix

@@ -33,10 +33,10 @@ stdenv.mkDerivation {
       PATH="$TMP/bin:$PATH"
     done
   '';
-  
+
   meta = {
     homepage = http://www.povray.org/;
     description = "Persistence of Vision Raytracer";
-    license = "free";
+    license = stdenv.lib.licenses.free;
   };
 }

pkgs/tools/graphics/welkin/default.nix

@@ -2,9 +2,9 @@ x@{builderDefsPackage
   , jre
   , ...}:
 builderDefsPackage
-(a :  
-let 
-  helperArgNames = ["stdenv" "fetchurl" "builderDefsPackage"] ++ 
+(a :
+let
+  helperArgNames = ["stdenv" "fetchurl" "builderDefsPackage"] ++
     ["jre"];
 
   buildInputs = map (n: builtins.getAttr n x)
@@ -39,7 +39,7 @@ rec {
     sed -e 's@[.]/lib/welkin[.]jar@"'"$out"'/share/welkin/lib/welkin.jar"@' -i "$out/share/welkin/welkin.sh"
     chmod a+x "$out/bin/welkin"
   '' ["minInit" "defEnsureDir"];
-      
+
   meta = {
     description = "An RDF visualizer";
     maintainers = with a.lib.maintainers;
@@ -47,7 +47,7 @@ rec {
       raskin
     ];
     hydraPlatforms = [];
-    license = "free-noncopyleft";
+    license = a.lib.licenses.free;
   };
   passthru = {
     updateInfo = {
@@ -55,4 +55,3 @@ rec {
     };
   };
 }) x
-