Force use of staging prefix for building Melbourne. Fixes #2630.
Force use of staging prefix for building Melbourne. Fixes #2630.

The issue is that when you configure with --prefix, running 'rake' will install. Now
the place that Rubinius was configure to run has a complete runtime directory structure.
So when you start up rbx during the build process with a subsequent 'rake install',
rbx will find the installed dirs, except we don't install the .rbc files because these
are cached during runtime in ~/.rbx if at all.

Short story is, 'rake; rake install' is redundant. Probably need to fix rake install
to note that rbx is already installed or something.

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