slp: Don't explode if there is some padding after end-of-row
slp: Don't explode if there is some padding after end-of-row

Many real SLPs (as found in SWGB/GRAPHICS.DRS) have a bit of air after
the end-of-row opcode. This isn't an error.

Signed-off-by: Chris Forbes <5dcac483e7a6e31a5cbe89f38cc69dff8ee93dac@ijw.co.nz>

fredreichbier/genie