support G, M, GiB, MiB, GB, MB, etc. shorthands in --maxrss arg

[andrewrk]

Extracted from #14647.

zig/lib/build_runner.zig

Lines 149 to 160 in b4d58e9

	} else if (mem.eql(u8, arg, "--maxrss")) {
	const max_rss_text = nextArg(args, &arg_idx) orelse {
	std.debug.print("Expected argument after --sysroot\n\n", .{});
	usageAndErr(builder, false, stderr_stream);
	};
	// TODO: support shorthand such as "2GiB", "2GB", or "2G"
	max_rss = std.fmt.parseInt(usize, max_rss_text, 10) catch |err| {
	std.debug.print("invalid byte size: '{s}': {s}\n", .{
	max_rss_text, @errorName(err),
	});
	process.exit(1);
	};

zig/lib/build_runner.zig

Line 952 in b4d58e9

\\ --maxrss <bytes> Limit memory usage (default is to use available memory)

I am currently testing a commit for this.