Turn off alloca.S - it cannot possibly work like this since on AMD64, gcc doesn't use stack frames.  It uses offsets relative to %rsp, not %rbp.  So we cannot just change %rsp like this.
Turn off alloca.S - it cannot possibly work like this since on AMD64, gcc
doesn't use stack frames.  It uses offsets relative to %rsp, not %rbp.  So
we cannot just change %rsp like this.

Approved by:	re (blanket amd64)

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