treewide: Add lots of platforms to packages with no meta

Build-tested on x86_64 Linux and on Darwin.

pkgs/tools/security/dirmngr/default.nix

@@ -7,4 +7,8 @@ stdenv.mkDerivation rec {
     sha256 = "1zz6m87ca55nq5f59hzm6qs48d37h93il881y7d0rf2d6660na6j";
   };
   buildInputs = [ libgpgerror libgcrypt libassuan libksba pth openldap ];
+
+  meta = {
+    platforms = stdenv.lib.platforms.linux;
+  };
 }

pkgs/tools/security/gnupg/1compat.nix

@@ -17,4 +17,8 @@ stdenv.mkDerivation {
     ${coreutils}/bin/ln -s gpg2 $out/bin/gpg
     ${coreutils}/bin/ln -s gpgv2 $out/bin/gpgv
   '';
+
+  meta = {
+    platforms = stdenv.lib.platforms.linux;
+  };
 }

pkgs/tools/security/mktemp/default.nix

@@ -11,4 +11,7 @@ stdenv.mkDerivation {
     sha256 = "1nfj89b0dv1c2fyqi1pg54fyzs3462cbp7jv7lskqsxvqy4mh9x1";
   };
   
+  meta = {
+    platforms = stdenv.lib.platforms.unix;
+  };
 }

pkgs/tools/security/mpw/default.nix

@@ -39,4 +39,8 @@ in stdenv.mkDerivation {
     mkdir -p $out/bin
     mv mpw $out/bin/mpw
   '';
+
+  meta = {
+    platforms = stdenv.lib.platforms.unix;
+  };
 }