Update spdlog: Allow syslog loggers on Mac

vendor/README

@@ -1,5 +1,6 @@
 This directory contains external projects, taken from the following locations:
 scrypt: http://www.tarsnap.com/scrypt.html
 googletest: https://github.com/google/googletest
-spdlog: https://github.com/gabime/spdlog/commit/0c7beb2e36008598cf80d0e8eb8635ac403febb9 (commit 0c7beb2e36008598cf80d0e8eb8635ac403febb9)
+spdlog: https://github.com/gabime/spdlog/commit/0c7beb2e36008598cf80d0e8eb8635ac403febb9
+- with own fix: https://github.com/cryfs/spdlog/commit/7b8d507615b8075fc6c8793a0965a32a708288c4
 gitversion: https://github.com/smessmer/gitversion

vendor/spdlog/spdlog/details/spdlog_impl.h

@@ -71,7 +71,7 @@ inline std::shared_ptr<spdlog::logger> spdlog::stderr_logger_st(const std::strin
     return details::registry::instance().create(logger_name, spdlog::sinks::stderr_sink_st::instance());
 }
 
-#ifdef __linux__
+#if defined(__linux__) || defined(__APPLE__)
 // Create syslog logger
 inline std::shared_ptr<spdlog::logger> spdlog::syslog_logger(const std::string& logger_name, const std::string& syslog_ident, int syslog_option)
 {

vendor/spdlog/spdlog/sinks/syslog_sink.h

@@ -5,7 +5,7 @@
 
 #pragma once
 
-#ifdef __linux__
+#if defined(__linux__) || defined(__APPLE__)
 
 #include <array>
 #include <string>

vendor/spdlog/spdlog/spdlog.h

@@ -78,7 +78,7 @@ std::shared_ptr<logger> stderr_logger_st(const std::string& logger_name);
 //
 // Create and register a syslog logger
 //
-#ifdef __linux__
+#if defined(__linux__) || defined(__APPLE__)
 std::shared_ptr<logger> syslog_logger(const std::string& logger_name, const std::string& ident = "", int syslog_option = 0);
 #endif