uclibc: arc: Add susv3 legacy alias bcmp

This fixes the building of screen package for ARC

Reported-by: Mischa Jonker <mjonker@synopsys.com>
Cc: Mischa Jonker <mjonker@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>