QEMU-KVM: Use `smbd' from $PATH.

svn path=/nixpkgs/trunk/; revision=32634

pkgs/os-specific/linux/qemu-kvm/default.nix

···
 
   patches = [ ./smb-tmpdir.patch ./qemu-img-fix-corrupt-vdi.patch ];
 
-  configureFlags = "--audio-drv-list=alsa";
+  configureFlags =
+    [ "--audio-drv-list=alsa"
+      "--smbd=smbd"                               # use `smbd' from $PATH
+    ];
 
   enableParallelBuilding = true;
 
···
     [ attr zlib SDL alsaLib pkgconfig pciutils libuuid vde2 libjpeg libpng
       ncurses python glib
     ];
-
-  preBuild =
-    ''
-      # Don't use a hardcoded path to Samba.
-      substituteInPlace ./net.h --replace /usr/sbin/smbd smbd
-    '';
 
   postInstall =
     ''