Promote libffi-dev as a general dependency

libffi-dev/libffi-devel can be requested for rebuilding the
python clients which is an un-skipable part of the devstack install.

Promoting the libffi-devel to a general dependency.

Change-Id: I1dac7fd536b94de1e49aaf335ac29ffae1bd39d1
diff --git a/files/rpms/general b/files/rpms/general
index a0074dd..74997a8 100644
--- a/files/rpms/general
+++ b/files/rpms/general
@@ -7,6 +7,7 @@
 openssh-server
 openssl
 openssl-devel # to rebuild pyOpenSSL if needed
+libffi-devel
 libxml2-devel
 libxslt-devel
 psmisc
diff --git a/files/rpms/glance b/files/rpms/glance
index fc07fa7..5a7f073 100644
--- a/files/rpms/glance
+++ b/files/rpms/glance
@@ -1,4 +1,3 @@
-libffi-devel
 libxml2-devel       # testonly
 libxslt-devel       # testonly
 mysql-devel         # testonly
diff --git a/files/rpms/swift b/files/rpms/swift
index 938d2c8..9ec4aab 100644
--- a/files/rpms/swift
+++ b/files/rpms/swift
@@ -1,5 +1,4 @@
 curl
-libffi-devel
 memcached
 python-configobj
 python-coverage