Add python-devel to rpms list for glance

It's needed to build the pysendfile module with pip.
This was fixed for Debian in 2be6155c6e4ad7bc0df61c47a1cfbb093a48b43d

Change-Id: I4ee2b12e2fd3fd9ea44420fdb44cc8ec339ff4fa
diff --git a/files/rpms/glance b/files/rpms/glance
index e38f239..eff6c2c 100644
--- a/files/rpms/glance
+++ b/files/rpms/glance
@@ -1,5 +1,6 @@
 libxml2-devel
 python-argparse
+python-devel
 python-eventlet
 python-greenlet
 python-paste-deploy