The /p4/common/site directory is to be used as a standard location for
storing any custom or site-specific files that are not part of the
SDP package that comes from Perforce Software.

The automated SDP upgrade procedure knows to ignore the /p4/common/site
directory tree.  The standard SDP shell environment mechanism includes
/p4/common/site/bin in the PATH, so that adding executable files in
there will put them in the PATH and thus make them easily accessible.

Files in the /p4/common/site tree are inherently custom and site-local,
and as such are not supported by Perforce Support.