Stack frame in execl_ is larger than allocated area on 64-bit

[W. J. van der Laan]

Hello,

I just noticed, by accident, that on 64-bit platforms the following array:

    char *c_argv[1000];

as defined in execl_ in src/posix.c is 8000 bytes, this is more than the 4260 bytes of stack frame allocated for every function in function-locals.

I think the fix is to change the 4 multiplier in x86_64:function-locals and riscv64:function-locals to 8?:

----------------------------------------------------------

(define (x86_64:function-locals . rest)

  `(

    ("sub____$i32,%rsp" (#:immediate ,(+ (* 4 1025) (* 20 8))))

    )) ; 4*1024 buf, 20 local vars

----------------------------------------------------------

As well as maybe detecting and throwing an error when this happens.

-W