README: Update requirements

pkg-conf and libssl-dev are needed for abuild to run successfully on
all boards.

Change-Id: Ic0ca2036751893ac4bd3ff17c53fe518b22b64ad
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: https://review.coreboot.org/20389
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
1 file changed