mod(options): build options to log to stderr and/or a file

NOTE: file logging will not work correctly yet due to opening files
appending using the std is currently not implemented (as of zig version
0.13.0)!

build.zig

@@ -6,9 +6,13 @@ const std = @import("std");
 pub fn build(b: *std.Build) void {
     // build options to customize the log message formating
     const include_timestamp = b.option(bool, "timestamp", "Enable inclusion of timestamps in log messages (default: true)") orelse true;
+    const stderr = b.option(bool, "stderr", "Print all log messages to stderr (default: true)") orelse true;
+    const file = b.option([]const u8, "file", "Print all log messages to the provided file.") orelse "";
 
     const options = b.addOptions();
     options.addOption(bool, "timestamp", include_timestamp);
+    options.addOption(bool, "stderr", stderr);
+    options.addOption([]const u8, "file", file);
 
     const options_module = options.createModule();