SDL: VisualC: turn on multi-processor compilation.

SDL Commits
1 
From a9ded76dff04cc24c8b49d2d3ff2533181798d1e Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Fri, 19 May 2023 01:35:08 -0400
Subject: [PATCH] VisualC: turn on multi-processor compilation.

This makes SDL2 build in 12 seconds, instead of 50, on my Windows
workstation, with Visual Studio.
---
 VisualC/SDL/SDL.vcxproj | 1 +
 1 file changed, 1 insertion(+)

diff --git a/VisualC/SDL/SDL.vcxproj b/VisualC/SDL/SDL.vcxproj
index 2c85790e2cab..957dabe1b398 100644
--- a/VisualC/SDL/SDL.vcxproj
+++ b/VisualC/SDL/SDL.vcxproj
@@ -137,6 +137,7 @@
       <DebugInformationFormat>OldStyle</DebugInformationFormat>
       <OmitDefaultLibName>true</OmitDefaultLibName>
       <InlineFunctionExpansion>OnlyExplicitInline</InlineFunctionExpansion>
+      <MultiProcessorCompilation>true</MultiProcessorCompilation>
     </ClCompile>
     <ResourceCompile>
       <PreprocessorDefinitions>_DEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>