nx-libs: minor fixes

* Add an alias with a deprecation warning for `nxproxy` to avoid an
  immediate breaking change.

* Use the default shell used in the build environment (`stdenv.shell`)
  for patching. This shell is in the environment and thus used to patch
  scripts using `patchShebangs`. The shell is referenced as `stdenv.shell`
  in Makefiles to patch the remaining occurrences of `/bin/bash` in the
  build environment.

pkgs/tools/X11/nx-libs/default.nix

@@ -20,8 +20,8 @@ stdenv.mkDerivation rec {
   enableParallelBuilding = true;
 
   postPatch = ''
-    find . -type f -executable -exec sed -i 's|^#!/bin/bash$|#!${bash}/bin/bash|g' {} \;
-    find . -type f -name Makefile -exec sed -i 's|^\(SHELL:=\)/bin/bash$|\1${bash}/bin/bash|g' {} \;
+    patchShebangs .
+    find . -type f -name Makefile -exec sed -i 's|^\(SHELL:=\)/bin/bash$|\1${stdenv.shell}|g' {} \;
     ln -s libNX_X11.so.6.3.0
   '';