don't use clock_cast with clang

libi2pd/FS.cpp

@@ -254,7 +254,7 @@ namespace fs {
 		std::error_code ec;
 		auto t = std::filesystem::last_write_time (path, ec);
 		if (ec) return 0;
-#if __cplusplus >= 202002L // C++ 20 or higher
+#if !defined(__clang__) && __cplusplus >= 202002L // C++ 20 or higher
 		const auto sctp = std::chrono::clock_cast<std::chrono::system_clock>(t);
 #else		
 		const auto sctp = std::chrono::time_point_cast<std::chrono::system_clock::duration>(

libi2pd/FS.h

@@ -15,7 +15,7 @@
 #include <sstream>
 #include <functional>
 
-#if (!(defined(_WIN32) && defined(__clang__)) && !defined(MAC_OSX) && !TARGET_OS_SIMULATOR && \
+#if (!defined(MAC_OSX) && !TARGET_OS_SIMULATOR && \
 	(__cplusplus >= 201703L) && defined(__cpp_lib_filesystem)) // C++ 17 or higher supporting filesystem
 #	define STD_FILESYSTEM 1
 #endif