Merge github.com:boostorg/pfr into develop

CMakeLists.txt

@@ -0,0 +1,20 @@
+# Generated by `boostdep --cmake pfr`
+# Copyright 2020 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+
+cmake_minimum_required(VERSION 3.5...3.16)
+
+project(boost_pfr VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)
+
+add_library(boost_pfr INTERFACE)
+add_library(Boost::pfr ALIAS boost_pfr)
+
+target_include_directories(boost_pfr INTERFACE include)
+
+if(BUILD_TESTING AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/test/CMakeLists.txt")
+
+  add_subdirectory(test)
+
+endif()
+