Include debug info when assembling win64.asm in a debug build.
diff --git a/PCbuild/_ctypes.vcproj b/PCbuild/_ctypes.vcproj
index d654a9b..b6abbe0 100644
--- a/PCbuild/_ctypes.vcproj
+++ b/PCbuild/_ctypes.vcproj
@@ -642,7 +642,7 @@
 					>
 					<Tool
 						Name="VCCustomBuildTool"
-						CommandLine="ml64 /nologo /c /Fo &quot;$(IntDir)\win64.obj&quot; &quot;$(InputPath)&quot;&#x0D;&#x0A;"
+						CommandLine="ml64 /nologo /c /Zi /Fo &quot;$(IntDir)\win64.obj&quot; &quot;$(InputPath)&quot;&#x0D;&#x0A;"
 						Outputs="$(IntDir)\win64.obj"
 					/>
 				</FileConfiguration>