dtv-scan-tables: set PREFIX=$out, put files in /share/dvbv5/..

This changes the output directory layout:
Channel files are placed in `$out/share/dvbv5/dvb-xyz`
instead of `$out/dvbv5/dvb-xyz`.
This is closer to the layout common for other packages
and facilitates merging packages with `buildEnv`.

The only depender `tvheadend` is updated accordingly.

pkgs/data/misc/dtv-scan-tables/default.nix

@@ -19,8 +19,8 @@ stdenv.mkDerivation rec {
     v4l-utils
   ];
 
-  installFlags = [
-    "DATADIR=$(out)"
+  makeFlags = [
+    "PREFIX=$(out)"
   ];
 
   meta = with lib; {

pkgs/servers/tvheadend/default.nix

@@ -105,7 +105,7 @@ in stdenv.mkDerivation {
       --replace /usr/bin/tar ${gnutar}/bin/tar
 
     substituteInPlace src/input/mpegts/scanfile.c \
-      --replace /usr/share/dvb ${dtv-scan-tables}/dvbv5
+      --replace /usr/share/dvb ${dtv-scan-tables}/share/dvbv5
 
     # the version detection script `support/version` reads this file if it
     # exists, so let's just use that