Only unignore directories that have at least a character ending with .cache

VisualStudio.gitignore

@@ -211,7 +211,7 @@ _pkginfo.txt
 # files ending in .cache can be ignored
 *.[Cc]ache
 # but keep track of directories ending in .cache
-!*.[Cc]ache/
+!?*.[Cc]ache/
 
 # Others
 ClientBin/