common/math_util: Move contents into the Common namespace

These types are within the common library, so they should be within the
Common namespace.

src/input_common/udp/client.cpp

@@ -217,7 +217,8 @@ void TestCommunication(const std::string& host, u16 port, u8 pad_index, u32 clie
             success_callback();
         else
             failure_callback();
-    }).detach();
+    })
+        .detach();
 }
 
 CalibrationConfigurationJob::CalibrationConfigurationJob(
@@ -268,7 +269,8 @@ CalibrationConfigurationJob::CalibrationConfigurationJob(
         complete_event.Wait();
         socket.Stop();
         worker_thread.join();
-    }).detach();
+    })
+        .detach();
 }
 
 CalibrationConfigurationJob::~CalibrationConfigurationJob() {