main/gexiv2: add gnu sed to makedepends (fixes musl build)

main/gexiv2/APKBUILD

@@ -9,7 +9,7 @@ arch="all"
 license="GPL"
 depends=
 depends_dev="glib-dev exiv2-dev"
-makedepends="exiv2-dev glib-dev libtool m4 gobject-introspection-dev"
+makedepends="exiv2-dev glib-dev libtool m4 sed gobject-introspection-dev"
 install=
 subpackages="$pkgname-dev"
 source="http://ftp.gnome.org/pub/gnome/sources/gexiv2/${pkgver%.*}/gexiv2-$pkgver.tar.xz"