Bump VERSION to v1.12.2-rc2

Signed-off-by: Victor Vieux <vieux@docker.com>
diff --git a/VERSION b/VERSION
index b01f5b9..93680b4 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.12.2-rc1
+1.12.2-rc2