rcp: Add profile to build only one rcp (one environment)

rcp: Add profile to build only one rcp (one environment)

When running validation builds (Gerrit trigger), we don't need
to build all environments. A failure to assemble the product on
only one platform is highly unlikely and would be caught by the
nightly build, at worse.

This patch adds a profile so that only one environment is built
(Linux 64).

Change-Id: Icba6d6a1b01da605db6fe19cceb2e3a2b3694315
Signed-off-by: Marc-Andre Laperle <marc-andre.laperle@ericsson.com>
Reviewed-on: https://git.eclipse.org/r/64784
Reviewed-by: Hudson CI