fix a bug where the label won't display content when setting its text in the interface builder
fix a bug where the label won't display content when setting its text in the interface builder

tranthanhvu/RQShineLabel,ChetanGandhi/RQShineLabel,zipme/RQShineLabel,KaiZhang890/RQShineLabel,maxkonovalov/RQShineLabel,mobitar/RQShineLabel,ysfox/RQShineLabel