community/mpd: allow configuration of real-time scheduling

Without this change MPD emits the following warnings using syslog:

	daemon.err libsmbclient[3356]: exception: RTIOThread could not
	  get realtime scheduling, continuing anyway: sched_setscheduler
	  failed: Operation not permitted
	daemon.err libsmbclient[3356]: exception: OutputThread could not
	  get realtime scheduling, continuing anyway: sched_setscheduler
	  failed: Operation not permitted

See also: https://www.musicpd.org/doc/html/user.html#real-time-scheduling

OK clandmeter@

1 files changed, 7 insertions, 2 deletions

diff --git a/community/mpd/APKBUILD b/community/mpd/APKBUILD
index 6d85088a6b..4e205a8526 100644
--- a/community/mpd/APKBUILD
+++ b/community/mpd/APKBUILD
@@ -9,7 +9,7 @@ case $pkgver in
 *.*.*) _branch=${pkgver%.*};;
 *.*) _branch=$pkgver;;
 esac
-pkgrel=5
+pkgrel=6
 pkgdesc="Music daemon that plays MP3, FLAC, Ogg Vorbis files and Audio CDs"
 url="https://musicpd.org"
 pkgusers="mpd"
@@ -20,7 +20,7 @@ makedepends="py3-sphinx lame-dev glib-dev curl-dev libao-dev libmad-dev flac-dev
         libogg-dev faad2-dev libid3tag-dev libvorbis-dev alsa-lib-dev
         libsamplerate-dev libshout-dev libmodplug-dev boost-dev icu-dev
         libnfs-dev samba-dev opus-dev ffmpeg-dev meson libmpdclient-dev
-        libcdio-paranoia-dev py3-attrs"
+        libcdio-paranoia-dev py3-attrs libcap"
 checkdepends="gtest-dev gtest"
 install="$pkgname.pre-install"
 subpackages="$pkgname-doc $pkgname-dbg $pkgname-openrc"
@@ -60,6 +60,11 @@ check() {
 package() {
         DESTDIR="$pkgdir" ninja -C output install
 
+        # mpd attempts to configure real-time scheduling on linux
+        # add the capability which allows doing that
+        # see: https://www.musicpd.org/doc/html/user.html#real-time-scheduling
+        setcap cap_sys_nice+ep "$pkgdir"/usr/bin/mpd
+
         # provide a config that works by default
         install -d "$pkgdir"/etc
         sed     -e 's:\#user.*:user\t\t"mpd":' \