Fix skfont crash on SB < 16. #1471

Job	Run time
raspi-2 / initialize	48s
raspi-2-skia / initialize	43s
raspi-2-skia / docker-build-image	2m 5s
raspi-2-skia / docker-unittest-image	0s
raspi-2 / docker-build-image	2m 16s
raspi-2 / docker-unittest-image	0s
raspi-2-skia / raspi-2-skia_devel	10m 28s
raspi-2-skia / raspi-2-skia_debug	14m 54s
raspi-2-skia / raspi-2-skia_qa	9m 16s
raspi-2-skia / raspi-2-skia_gold	8m 47s
raspi-2 / raspi_devel	10m 36s
raspi-2 / raspi_debug	13m 54s
raspi-2 / raspi_qa	9m 6s
raspi-2 / raspi_gold	9m 13s
raspi-2 / sbversion-15_devel	10m 36s
raspi-2 / sbversion-15_debug	16m 0s
raspi-2 / sbversion-15_qa	9m 2s
raspi-2 / sbversion-15_gold	8m 53s
raspi-2 / sbversion-16_devel	10m 3s
raspi-2 / sbversion-16_debug	14m 27s
raspi-2 / sbversion-16_qa	9m 16s
raspi-2 / sbversion-16_gold	9m 51s
raspi-2-skia / ${{ matrix.name }}_${{ matrix.shard }}_test	0s
raspi-2-skia / ${{ matrix.name }}_on_device_${{ matrix.shard }}	0s
raspi-2 / ${{ matrix.name }}_${{ matrix.shard }}_test	0s
raspi-2 / ${{ matrix.name }}_on_device_${{ matrix.shard }}	0s
	3h 0m 14s

Provide feedback