testing/mpv: set confdir

ref #2438

testing/mpv/APKBUILD

@@ -2,7 +2,7 @@
 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=mpv
 pkgver=0.2.4
-pkgrel=0
+pkgrel=1
 pkgdesc="Video player based on MPlayer/mplayer2"
 url="http://mpv.io/"
 arch="all"
@@ -34,6 +34,7 @@ build() {
 	cd "$_builddir"
 	./configure --prefix=/usr \
 		--mandir=/usr/share/man \
+		--confdir=/etc/mpv \
 		|| return 1
 	make || return 1
 }