rtg-tools: fix runtime error

On a new testing machine, dirname is not available
in the PATH  during execution.

pkgs/by-name/rt/rtg-tools/package.nix

@@ -50,7 +50,9 @@ stdenv.mkDerivation (finalAttrs: {
        --replace-fail 'RTG_JAVA="java"' 'RTG_JAVA="${lib.getExe jdk}"' \
       --replace-fail uname ${lib.getExe' coreutils "uname"} \
       --replace-fail awk ${lib.getExe gawk} \
-      --replace-fail "hostname -s" "${lib.getExe hostname} -s"
+      --replace-fail "hostname -s" "${lib.getExe hostname} -s" \
+      --replace-fail dirname ${lib.getExe' coreutils "dirname"} \
+      --replace-fail readlink ${lib.getExe' coreutils "readlink"}
 
     sed -i '/USER_JAVA_OPTS=$RTG_JAVA_OPTS/a mkdir -p $HOME/.config/rtg-tools'  installer/rtg
   '';