Timing: Optimize Timestamp Aquisition (#479)

* Timing: Optimize Timestamp Aquisition

Currently, we make use of Environment.TickCount in a number of places. This has some downsides, mainly being that the TickCount is a signed 32-bit integer, and has an effective limit of ~25 days before overflowing and wrapping around. Due to the signed-ness of the value, this also caused issues with negative numbers. This resolves these issues by using a 64-bit tick count obtained from Performance Counters (via the Stopwatch class). This has a beneficial side effect of being significantly more accurate than the TickCount.

* Timing: Rename ElapsedTicks to ElapsedMilliseconds and expose TicksPerX

* Timing: Some style changes

* Timing: Align static variable initialization

Ryujinx.Common/PerformanceCounter.cs

@@ -0,0 +1,65 @@
+using System.Diagnostics;
+
+namespace Ryujinx.Common
+{
+    public static class PerformanceCounter
+    {
+        /// <summary>
+        /// Represents the number of ticks in 1 day.
+        /// </summary>
+        public static long TicksPerDay { get; }
+
+        /// <summary>
+        /// Represents the number of ticks in 1 hour.
+        /// </summary>
+        public static long TicksPerHour { get; }
+
+        /// <summary>
+        /// Represents the number of ticks in 1 minute.
+        /// </summary>
+        public static long TicksPerMinute { get; }
+
+        /// <summary>
+        /// Represents the number of ticks in 1 second.
+        /// </summary>
+        public static long TicksPerSecond { get; }
+
+        /// <summary>
+        /// Represents the number of ticks in 1 millisecond.
+        /// </summary>
+        public static long TicksPerMillisecond { get; }
+
+        /// <summary>
+        /// Gets the number of milliseconds elapsed since the system started.
+        /// </summary>
+        public static long ElapsedTicks
+        {
+            get
+            {
+                return Stopwatch.GetTimestamp();
+            }
+        }
+
+        /// <summary>
+        /// Gets the number of milliseconds elapsed since the system started.
+        /// </summary>
+        public static long ElapsedMilliseconds
+        {
+            get
+            {
+                long timestamp = Stopwatch.GetTimestamp();
+
+                return timestamp / TicksPerMillisecond;
+            }
+        }
+
+        static PerformanceCounter()
+        {
+            TicksPerMillisecond = Stopwatch.Frequency / 1000;
+            TicksPerSecond      = Stopwatch.Frequency;
+            TicksPerMinute      = TicksPerSecond * 60;
+            TicksPerHour        = TicksPerMinute * 60;
+            TicksPerDay         = TicksPerHour * 24;
+        }
+    }
+}