[dwg] The stack frame itself probably isn't that big a deal, but
avoiding alloca() is generally recommended these days.

Signed-off-by: Elena Afanasova <eafanasova@gmail.com>
Message-Id: <8f07132478469b35fb50a4706691e2b56b10a67b.camel@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>