samba4: Add extra useful dependencies and attempt to fix darwin build

pkgs/servers/samba/4.x-fix-ctdb-deps.patch

···
+diff --git a/ctdb/wscript b/ctdb/wscript
+index 3e2a992..3fe15cc 100755
+--- a/ctdb/wscript
++++ b/ctdb/wscript
+@@ -568,7 +568,7 @@ def build(bld):
+                          source='ib/ibwrapper_test.c',
+                          includes='include include/internal',
+                          deps='''replace talloc ctdb-client ctdb-common
+-                                 ctdb-system''' +
++                                 ctdb-system ctdb-common-util''' +
+                               ib_deps,
+                          install_path='${CTDB_TEST_LIBDIR}')
+ 

pkgs/servers/samba/4.x.nix

···
 , zlib ? null
 , ncurses ? null
 , libcap ? null
+, libunwind ? null
+, dbus ? null
+, libibverbs ? null
+, librdmacm ? null
+, systemd ? null
 }:
 
 stdenv.mkDerivation rec {
···
   patches = [
     ./4.x-no-persistent-install.patch
     ./4.x-heimdal-compat.patch
+    ./4.x-fix-ctdb-deps.patch
   ];
 
   buildInputs = [
···
 
     gnutls libgcrypt libgpgerror
 
-    zlib ncurses libcap
+    zlib ncurses libcap libunwind dbus libibverbs librdmacm systemd
   ];
 
   postPatch = ''

pkgs/top-level/all-packages.nix

···
     libgcrypt = libgcrypt_1_6;
     python = python2;
     pythonPackages = python2Packages;
+    cups = if stdenv.isDarwin then null else cups;
+    pam = if stdenv.isDarwin then null else pam;
+    libaio = if stdenv.isDarwin then null else libaio;
+    ceph = if stdenv.isDarwin then null else ceph;
+    glusterfs = if stdenv.isDarwin then null else glusterfs;
+    libcap = if stdenv.isLinux then libcap else null;
+    dbus = if stdenv.isLinux then dbus else null;
+    libibverbs = if stdenv.isLinux then libibverbs else null;
+    librdmacm = if stdenv.isLinux then librdmacm else null;
+    systemd = if stdenv.isLinux then system else null;
   };
 
   samba = samba4;