lcall7 and lcall27 code paths are almost identical, except one
constant. This code merges these two paths together, by moving
constant to the beginning of function.

It is possible to eliminate even more of lcall7 and lcall27
code paths, but at cost of splitting SAVE_ALL into two halves,
and I do not want to do that. But if you think that it is worth
of effort, I can save 16 more bytes, but at cost of speed.

Side effects of merge is that now stack is addressed relative
to %ebx instead of relative to %esp, so generated code is
shorter and faster.