Ignore PCbuild/.vs directory.

Also fix a couple other ignored PCbuild directories in .gitignore
diff --git a/.hgignore b/.hgignore
index 7a52606..806e156 100644
--- a/.hgignore
+++ b/.hgignore
@@ -73,6 +73,7 @@
 PCbuild/*.*sdf
 PCbuild/*-pgi
 PCbuild/*-pgo
+PCbuild/.vs
 PCbuild/amd64
 PCbuild/obj
 PCbuild/win32