cmssw-dictdb,cmssw-dictdb-toolfile: new external

The following external is used to store Reflex and CINT dictionaries
generated on x86_64 to be used on aarch64 (ARMv8).

The instructions how to generate the content (alldicts.zip) is in
cmssw-dictdb.spec

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
local-princeton-siteconf: new external

The following external adds SITECONF to be used on Princeton T3 for
development purposes.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
root-toolfile: remove root_dictcache.xml

Remove root_dictcache.xml from ROOT toolfile. It is now part of
cmssw-dictdb toolfile.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
cmssw-tool-conf: add dependency on cmssw-dictdb-toolfile

Use pre-generated Reflex dictionaries if we are running on aarch64.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>