debug/dmalloc: enforce cross-compilation

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Message-Id: <69772732f551aa342a2c.1363446264@laptop>
Patchwork-Id: 228221

 #!/bin/sh

 set -e

 printf "Running autoconf...\n"

 autoconf -Wall --force

 printf "Done. You may now run:\n    ./configure\n"