Add the 'json' package. Code taken from simplejson 1.9 and contributed by Bob
Ippolito.

Closes issue #2750.
diff --git a/PCbuild/pythoncore.vcproj b/PCbuild/pythoncore.vcproj
index d8c1cdf..583a32b 100644
--- a/PCbuild/pythoncore.vcproj
+++ b/PCbuild/pythoncore.vcproj
@@ -1007,6 +1007,10 @@
 				>
 			</File>
 			<File
+				RelativePath="..\Modules\_json.c"
+				>
+			</File>
+			<File
 				RelativePath="..\Modules\_localemodule.c"
 				>
 			</File>