notmuch: stop trying to patch gpg paths in emacs/notmuch-crypto.el

This was fixed upstream in f0d06c8ca3fce15c9e264445485bd93a6de8d25e, by
using epg-gpg-program instead of `(call-process epg-gpg-program …)` as
before.

pkgs/applications/networking/mailreaders/notmuch/default.nix

@@ -47,8 +47,7 @@ stdenv.mkDerivation rec {
 
     for src in \
       util/crypto.c \
-      notmuch-config.c \
-      emacs/notmuch-crypto.el
+      notmuch-config.c
     do
       substituteInPlace "$src" \
         --replace \"gpg\" \"${gnupg}/bin/gpg\"