Clear out some duplicate package dependencies

I think these duplicate dependencies came in because we were not
correctly always installing "general" packages (see
Ie1b8d09369281059d21da61b2725a457f708ae9e)

Most of these are just extras for the lxml dependencies; I added zlib
devel to general for glance (seems pretty generic), and then that can
go too, as all other packages are specified.

Change-Id: I44b14ca15c64fad9daf1ac8d851704b02ea2eae0
diff --git a/files/rpms/general b/files/rpms/general
index 2a45227..eb479d2 100644
--- a/files/rpms/general
+++ b/files/rpms/general
@@ -32,3 +32,4 @@
 mariadb-devel  # MySQL-python
 postgresql-devel  # psycopg2
 redhat-rpm-config # MySQL-python rhbz-1195207 f21
+zlib-devel