Allow RUBYLIB to be set, but issue a huge warning.
Allow RUBYLIB to be set, but issue a huge warning.

It's possible the user has a really good reason for setting RUBYLIB. In this
case, we shouldn't force an exit. Unknowing users will get a warning, which
they can choose to heed. At least errors from RUBYLIB being set won't be as
hidden as before we added the check.

Wirachmat/rubinius,sferik/rubinius,jemc/rubinius,sferik/rubinius,Wirachmat/rubinius,Azizou/rubinius,digitalextremist/rubinius,mlarraz/rubinius,ruipserra/rubinius,ruipserra/rubinius,benlovell/rubinius,Wirachmat/rubinius,mlarraz/rubinius,jsyeo/rubinius,jsyeo/rubinius,mlarraz/rubinius,jsyeo/rubinius,jemc/rubinius,kachick/rubinius,ngpestelos/rubinius,jemc/rubinius,jemc/rubinius,digitalextremist/rubinius,ngpestelos/rubinius,kachick/rubinius,benlovell/rubinius,mlarraz/rubinius,dblock/rubinius,kachick/rubinius,pH14/rubinius,Azizou/rubinius,ruipserra/rubinius,digitalextremist/rubinius,mlarraz/rubinius,sferik/rubinius,Azizou/rubinius,benlovell/rubinius,pH14/rubinius,benlovell/rubinius,heftig/rubinius,heftig/rubinius,Wirachmat/rubinius,jemc/rubinius,ngpestelos/rubinius,kachick/rubinius,Azizou/rubinius,ngpestelos/rubinius,kachick/rubinius,digitalextremist/rubinius,dblock/rubinius,Wirachmat/rubinius,kachick/rubinius,jemc/rubinius,sferik/rubinius,kachick/rubinius,heftig/rubinius,ruipserra/rubinius,jsyeo/rubinius,digitalextremist/rubinius,dblock/rubinius,ruipserra/rubinius,heftig/rubinius,heftig/rubinius,pH14/rubinius,benlovell/rubinius,ruipserra/rubinius,pH14/rubinius,mlarraz/rubinius,jsyeo/rubinius,jsyeo/rubinius,heftig/rubinius,Azizou/rubinius,Wirachmat/rubinius,benlovell/rubinius,dblock/rubinius,dblock/rubinius,sferik/rubinius,ngpestelos/rubinius,dblock/rubinius,digitalextremist/rubinius,benlovell/rubinius,sferik/rubinius,Azizou/rubinius,heftig/rubinius,pH14/rubinius,dblock/rubinius,ruipserra/rubinius,jsyeo/rubinius,Azizou/rubinius,ngpestelos/rubinius,mlarraz/rubinius,pH14/rubinius,sferik/rubinius,Wirachmat/rubinius,kachick/rubinius,pH14/rubinius,ngpestelos/rubinius,digitalextremist/rubinius,jemc/rubinius