adding mic headers, switching to runtime dynamic libloading

examples/enumerate.zig

@@ -2,6 +2,9 @@ const std = @import("std");
 const mic = @import("miclib");
 
 pub fn main() !void {
+    try mic.load();
+    defer mic.unload();
+
     var devices = mic.DeviceList.init() catch |err| {
         std.debug.print("mic_get_devices failed: {s}\n", .{@errorName(err)});
         printLastMicError();