Revert "better overriding of conf dir"

This reverts commit 00f5e1d285.

confdir.patch

@@ -0,0 +1,13 @@
+diff --git a/meson.build b/meson.build
+index acaa39f764..b4efc581dc 100644
+--- a/meson.build
++++ b/meson.build
+@@ -1625,7 +1625,7 @@ sys.stdout.write(features)
+ '''
+ feature_str = run_command(python, '-c', feature_sort, feature_keys, check: true).stdout()
+ conf_data.set_quoted('FULLCONFIG', feature_str)
+-conf_data.set_quoted('MPV_CONFDIR', join_paths(get_option('prefix'), get_option('sysconfdir'), 'mpv'))
++conf_data.set_quoted('MPV_CONFDIR', '/etc/mpv')
+ configure_file(output : 'config.h', configuration : conf_data)
+ message('List of enabled features: ' + feature_str)
+ 

flake.nix

@@ -48,8 +48,8 @@
         newScripts = packages.packages.${prev.system};
       in rec {
         mpv-unwrapped = prev.mpv-unwrapped.overrideAttrs (oldAttrs: {
-          wafConfigureFlags = oldAttrs.wafConfigureFlags ++ [
-            "--confloaddir=/etc/mpv"
+          patches = (oldAttrs.patches or []) ++ [
+            ./confdir.patch
           ];
         });
         mpv = prev.wrapMpv mpv-unwrapped {