glibmm, gtkmm: build on Darwin

pkgs/development/libraries/glibmm/default.nix

@@ -25,6 +25,6 @@ stdenv.mkDerivation rec {
     license = stdenv.lib.licenses.lgpl2Plus;
 
     maintainers = with stdenv.lib.maintainers; [urkud raskin];
-    platforms = stdenv.lib.platforms.linux;
+    platforms = stdenv.lib.platforms.unix;
   };
 }

pkgs/development/libraries/gtkmm/2.x.nix

@@ -33,6 +33,6 @@ stdenv.mkDerivation rec {
     license = stdenv.lib.licenses.lgpl2Plus;
 
     maintainers = with stdenv.lib.maintainers; [ raskin vcunat ];
-    platforms = stdenv.lib.platforms.linux;
+    platforms = stdenv.lib.platforms.unix;
   };
 }

pkgs/development/libraries/gtkmm/3.x.nix

@@ -37,6 +37,6 @@ stdenv.mkDerivation rec {
     license = stdenv.lib.licenses.lgpl2Plus;
 
     maintainers = with stdenv.lib.maintainers; [ raskin urkud vcunat ];
-    platforms = stdenv.lib.platforms.linux;
+    platforms = stdenv.lib.platforms.unix;
   };
 }