Installation: Add Gentoo ebuild

This commit adds an ebuild for Gentoo. Version 9999 is building live
from current git, currently using kakra:integration because it has some
installation and build fixes important for Gentoo.

Signed-off-by: Kai Krakow <kai@kaishome.de>

contrib/gentoo/bees-9999.ebuild

@@ -0,0 +1,42 @@
+# Copyright 1999-2018 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=6
+
+inherit git-r3 eutils multilib
+
+DESCRIPTION="Best-Effort Extent-Same, a btrfs dedup agent"
+HOMEPAGE="https://github.com/Zygo/bees"
+
+if [[ ${PV} == "9999" ]] ; then
+	EGIT_REPO_URI="https://github.com/kakra/bees.git"
+	EGIT_BRANCH="integration"
+else
+	IUSE=""
+
+	SRC_URI="https://github.com/Zygo/bees/archive/v${PV}.tar.gz -> bees-${PV}.tar.gz"
+fi
+
+PATCHES="
+	${FILESDIR}/v0.5-gentoo_build.patch
+"
+
+LICENSE="GPL-3"
+SLOT="0"
+KEYWORDS=""
+IUSE=""
+
+DEPEND="
+	>=sys-apps/util-linux-2.30.2
+	>=sys-devel/gcc-4.9
+	>=sys-fs/btrfs-progs-4.1
+"
+RDEPEND="${DEPEND}"
+
+DOCS="README.md COPYING"
+HTML_DOCS="README.html"
+
+src_prepare() {
+	default
+	echo LIBDIR=$(get_libdir) >>${S}/localconf
+}