Add a newer spdlog

Spdlog in portage depends on libfmt 5, now libfmt 6 is stable

dev-libs/spdlog/Manifest

@@ -0,0 +1 @@
+DIST spdlog-1.4.2.tar.gz 260262 BLAKE2B 1dda9d311b7832d638b0764e21075b67ee8e59b8f013b7f88eeb773093117cb50ae9325aaedcb94101b9980132ddbe8147e7e52a79856e2766ac51258b3c4de1 SHA512 886b489138a1bdf363b5eab65a7d973f570a01c399ff5b910fcfee172ad4ff4d42a45dc2ae24e77b07130df527fb13a86b3e55ac992e72c418aebb232e27eabf

dev-libs/spdlog/files/spdlog-1.4.2-include-assert.patch

@@ -0,0 +1,21 @@
+--- a/include/spdlog/details/pattern_formatter-inl.h	2019-10-06 13:13:26.000000000 +0300
++++ b/include/spdlog/details/pattern_formatter-inl.h	2020-01-07 10:05:01.333785629 +0200
+@@ -24,6 +24,7 @@
+ #include <thread>
+ #include <utility>
+ #include <vector>
++#include <cassert>
+ 
+ namespace spdlog {
+ namespace details {
+--- a/include/spdlog/details/thread_pool-inl.h	2019-10-06 13:13:26.000000000 +0300
++++ b/include/spdlog/details/thread_pool-inl.h	2020-01-07 10:05:01.330452318 +0200
+@@ -9,6 +9,8 @@
+ 
+ #include "spdlog/common.h"
+ 
++#include <cassert>
++
+ namespace spdlog {
+ namespace details {
+ 

dev-libs/spdlog/spdlog-1.4.2.ebuild

@@ -0,0 +1,42 @@
+# Copyright 1999-2020 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=7
+
+inherit cmake
+
+DESCRIPTION="Very fast, header only, C++ logging library"
+HOMEPAGE="https://github.com/gabime/spdlog"
+
+if [[ ${PV} == *9999 ]]; then
+	inherit git-r3
+	EGIT_REPO_URI="https://github.com/gabime/spdlog"
+else
+	SRC_URI="https://github.com/gabime/spdlog/archive/v${PV}.tar.gz -> ${P}.tar.gz"
+	KEYWORDS="~amd64"
+fi
+
+LICENSE="MIT"
+SLOT="0/1"
+IUSE="test"
+RESTRICT="!test? ( test )"
+
+DEPEND="
+	dev-libs/libfmt:0/6
+"
+RDEPEND="${DEPEND}"
+
+PATCHES=( "${FILESDIR}/${PN}-1.4.2-include-assert.patch" )
+
+src_configure() {
+	rm -r include/spdlog/fmt/bundled || die
+
+	local mycmakeargs=(
+		-DSPDLOG_BUILD_EXAMPLE=no
+		-DSPDLOG_BUILD_BENCH=no
+		-DSPDLOG_BUILD_TESTS=$(usex test)
+		-DSPDLOG_FMT_EXTERNAL=1
+	)
+
+	cmake_src_configure
+}