Haiku: fix adding resources

The custom_command was run in src/haiku/ and created a file with only resources inside.

Since xres edits the file in-place and meson doesn't like it, we have to run a shell script for now.
Maybe later I'll add proper support in meson.

src/haiku/add_resources.sh

@@ -0,0 +1,3 @@
+#!/bin/sh
+
+cp "$2" "$1" && xres -o "$1" -- "$3" && mimeset -f "$1" || (rm -f "$1"; exit 1)

src/haiku/meson.build

@@ -8,11 +8,4 @@ rsrc = custom_target(
   command: [rc, '-o', '@OUTPUT@', '@INPUT@'],
 )
 
-custom_target(
-  'mpd.xres',
-  output: 'mpd',
-  input: [mpd, rsrc],
-  command: [xres, '-o', '@OUTPUT@', '--', '@INPUT@'],
-  install: true,
-  install_dir: get_option('bindir'),
-)
+addres = files('add_resources.sh')