Switched to header only spdlog for better portability

thirdparty/spdlog/fmt/fmt.h

@@ -0,0 +1,27 @@
+//
+// Copyright(c) 2016-2018 Gabi Melman.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+//
+
+#pragma once
+
+//
+// Include a bundled header-only copy of fmtlib or an external one.
+// By default spdlog include its own copy.
+//
+
+#if !defined(SPDLOG_FMT_EXTERNAL)
+#    if !defined(SPDLOG_COMPILED_LIB) && !defined(FMT_HEADER_ONLY)
+#        define FMT_HEADER_ONLY
+#    endif
+#    ifndef FMT_USE_WINDOWS_H
+#        define FMT_USE_WINDOWS_H 0
+#    endif
+// enable the 'n' flag in for backward compatibility with fmt 6.x
+#    define FMT_DEPRECATED_N_SPECIFIER
+#    include <spdlog/fmt/bundled/core.h>
+#    include <spdlog/fmt/bundled/format.h>
+#else // SPDLOG_FMT_EXTERNAL is defined - use external fmtlib
+#    include <fmt/core.h>
+#    include <fmt/format.h>
+#endif