skawarePackages: support static builds via pkgsStatic

Most of the skaware packages already build just fine with pkgsStatic,
however the wrapper scripts for execline and stdnotify-wrapper needed
the `-lskarlib` argument to go at the end.

`utmps` and `nsss` still fail with this error:

```
exec ./tools/install.sh -D -m 600 utmps-utmpd /bin/utmps-utmpd
/build/utmps-0.0.3.1/tools/install.sh: line 48: can't create /bin/utmps-utmpd.tmp.479: Permission denied
make: *** [Makefile:121: /bin/utmps-utmpd] Error 1
```

pkgs/build-support/skaware/build-skaware-package.nix

@@ -65,6 +65,9 @@ in stdenv.mkDerivation {
 
   configureFlags = configureFlags ++ [
     "--enable-absolute-paths"
+    # We assume every nix-based cross target has urandom.
+    # This might not hold for e.g. BSD.
+    "--with-sysdep-devurandom=yes"
     (if stdenv.isDarwin
       then "--disable-shared"
       else "--enable-shared")