simd4x4f: Simplify the perspective() function
simd4x4f: Simplify the perspective() function

Use the newly added merge_w() operator for SIMD vectors to cut some
lines out. The function could be unrolled differently by using a
transposed matrix and accessing the column vectors, but it would need
to be benchmarked first.

criptych/graphene,criptych/graphene,ebassi/graphene,ebassi/graphene,criptych/graphene,criptych/graphene