Reverted accidental Visual Studio version bump in SDL.sln

VisualC/SDL.sln

@@ -1,7 +1,5 @@
-Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio Version 16
-VisualStudioVersion = 16.0.31402.337
-MinimumVisualStudioVersion = 10.0.40219.1
+Microsoft Visual Studio Solution File, Format Version 11.00
+# Visual Studio 2010
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{D69D5741-611F-4E14-8541-1FEE94F50B5A}"
 EndProject
 Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "SDL2", "SDL\SDL.vcxproj", "{81CE8DAF-EBB2-4761-8E45-B71ABCCA8C68}"