This commit allows `num_coords' to be larger or smaller than the
number of available axes while selecting a design instance, either
ignoring excess data or using defaults if data is missing.
* src/truetype/ttgxvar.c (TT_Set_MM_Blend, TT_Set_Var_Design):
Implement it.
* src/type1/t1load.c (T1_Set_MM_Blend, T1_Set_MM_Design,
T1_Set_Var_Design): Ditto.