GPencil: Fix sharp_threshold property in sample stroke operator

The property registration was missing in the operator, now fixed.

source/blender/editors/gpencil/gpencil_edit.c

@@ -4483,6 +4483,7 @@ void GPENCIL_OT_stroke_sample(wmOperatorType *ot)
 
   /* properties */
   prop = RNA_def_float(ot->srna, "length", 0.1f, 0.0f, 100.0f, "Length", "", 0.0f, 100.0f);
+  prop = RNA_def_float(ot->srna, "sharp_threshold", 0.1f, 0.0f, M_PI, "Sharp Threshold", "", 0.0f, M_PI);
   /* avoid re-using last var */
   RNA_def_property_flag(prop, PROP_SKIP_SAVE);
 }