Merge pull request MessagePack-CSharp#1481 from ValkaVales/patch-1

Fix OverflowException in SafeBitConverter.ToInt64

Author: AArnott

src/MessagePack.UnityClient/Assets/Scripts/MessagePack/SafeBitConverter.cs

@@ -13,15 +13,15 @@ internal static long ToInt64(ReadOnlySpan<byte> value)
 #if UNITY_ANDROID
             if (BitConverter.IsLittleEndian)
             {
-                int i1 = value[0] | (value[1] << 8) | (value[2] << 16) | (value[3] << 24);
-                int i2 = value[4] | (value[5] << 8) | (value[6] << 16) | (value[7] << 24);
-                return (uint)i1 | ((long)i2 << 32);
+                long i1 = value[0] | (value[1] << 8) | (value[2] << 16) | (value[3] << 24);
+                long i2 = value[4] | (value[5] << 8) | (value[6] << 16) | (value[7] << 24);
+                return i1 | (i2 << 32);
             }
             else
             {
-                int i1 = (value[0] << 24) | (value[1] << 16) | (value[2] << 8) | value[3];
-                int i2 = (value[4] << 24) | (value[5] << 16) | (value[6] << 8) | value[7];
-                return (uint)i2 | ((long)i1 << 32);
+                long i1 = (value[0] << 24) | (value[1] << 16) | (value[2] << 8) | value[3];
+                long i2 = (value[4] << 24) | (value[5] << 16) | (value[6] << 8) | value[7];
+                return i2 | (i1 << 32);
             }
 #else
             return MemoryMarshal.Cast<byte, long>(value)[0];