coreutils,gettext: don't change hash except for darwin

Also some style cleanup.
Note that defining an empty-string variable *does* change the hash.
I would like to change this behaviour one day
(clean up attrs when compiling the derivation).

pkgs/development/libraries/gettext/default.nix

@@ -1,8 +1,10 @@
-{ stdenv, fetchurl, libiconv }:
+{ stdenv, fetchurl, libiconvOrEmpty }:
+
+with { inherit (stdenv.lib) optionals optionalAttrs; };
 
 stdenv.mkDerivation (rec {
   name = "gettext-0.18.1.1";
-  
+
   src = fetchurl {
     url = "mirror://gnu/gettext/${name}.tar.gz";
     sha256 = "1sa3ch12qxa4h3ya6hkz119yclcccmincl9j20dhrdx5mykp3b4k";
@@ -11,7 +13,7 @@ stdenv.mkDerivation (rec {
   patches = [ ./no-gets.patch ];
 
   configureFlags = [ "--disable-csharp" ]
-     ++ (stdenv.lib.optionals stdenv.isCygwin
+     ++ (optionals stdenv.isCygwin
           [ # We have a static libiconv, so we can only build the static lib.
             "--disable-shared" "--enable-static"
 
@@ -19,9 +21,6 @@ stdenv.mkDerivation (rec {
             "--config-cache"
           ]);
 
-  makeFlags = stdenv.lib.optionalString stdenv.isDarwin
-    "CFLAGS=-D_FORTIFY_SOURCE=0";
-
   # On cross building, gettext supposes that the wchar.h from libc
   # does not fulfill gettext needs, so it tries to work with its
   # own wchar.h file, which does not cope well with the system's
@@ -33,12 +32,12 @@ stdenv.mkDerivation (rec {
     fi
   '';
 
-  buildInputs = stdenv.lib.optional (!stdenv.isLinux) libiconv;
-  
+  buildInputs = libiconvOrEmpty;
+
   enableParallelBuilding = true;
-      
+
   crossAttrs = {
-    buildInputs = stdenv.lib.optional (stdenv.gccCross.libc ? libiconv)
+    buildInputs = optional (stdenv.gccCross.libc ? libiconv)
       stdenv.gccCross.libc.libiconv.crossDrv;
     # Gettext fails to guess the cross compiler
     configureFlags = "CXX=${stdenv.cross.config}-g++";
@@ -73,9 +72,11 @@ stdenv.mkDerivation (rec {
   };
 }
 
-//
+// optionalAttrs stdenv.isDarwin {
+  makeFlags = "CFLAGS=-D_FORTIFY_SOURCE=0";
+}
 
-stdenv.lib.optionalAttrs stdenv.isCygwin {
+// optionalAttrs stdenv.isCygwin {
   patchPhase =
    # Make sure `error.c' gets compiled and is part of `libgettextlib.la'.
    # This fixes:

pkgs/tools/misc/coreutils/default.nix

@@ -6,8 +6,11 @@
 assert aclSupport -> acl != null;
 assert selinuxSupport -> libselinux != null && libsepol != null;
 
+
+with { inherit (stdenv.lib) optional optionals optionalString optionalAttrs; };
+
 let
-  self = stdenv.mkDerivation rec {
+  self = stdenv.mkDerivation (rec {
     name = "coreutils-8.21";
 
     src = fetchurl {
@@ -17,16 +20,14 @@ let
 
     nativeBuildInputs = [ perl ];
     buildInputs = [ gmp ]
-      ++ stdenv.lib.optional aclSupport acl
-      ++ stdenv.lib.optional selinuxSupport libselinux
-      ++ stdenv.lib.optional selinuxSupport libsepol;
+      ++ optional aclSupport acl
+      ++ optionals selinuxSupport [ libselinux libsepol ];
 
     crossAttrs = {
       buildInputs = [ gmp ]
-        ++ stdenv.lib.optional aclSupport acl.crossDrv
-        ++ stdenv.lib.optional selinuxSupport libselinux.crossDrv
-        ++ stdenv.lib.optional selinuxSupport libsepol.crossDrv
-        ++ stdenv.lib.optional (stdenv.gccCross.libc ? libiconv)
+        ++ optional aclSupport acl.crossDrv
+        ++ optionals selinuxSupport [ libselinux.crossDrv libsepol.crossDrv ]
+        ++ optional (stdenv.gccCross.libc ? libiconv)
           stdenv.gccCross.libc.libiconv.crossDrv;
 
       buildPhase = ''
@@ -57,10 +58,7 @@ let
 
     enableParallelBuilding = true;
 
-    NIX_LDFLAGS = stdenv.lib.optionalString selinuxSupport "-lsepol";
-
-    makeFlags = stdenv.lib.optionalString stdenv.isDarwin
-      "CFLAGS=-D_FORTIFY_SOURCE=0";
+    NIX_LDFLAGS = optionalString selinuxSupport "-lsepol";
 
     meta = {
       homepage = http://www.gnu.org/software/coreutils/;
@@ -77,6 +75,8 @@ let
 
       maintainers = [ ];
     };
-  };
+  } // optionalAttrs stdenv.isDarwin {
+    makeFlags = "CFLAGS=-D_FORTIFY_SOURCE=0";
+  });
 in
   self