qemu-build: Remove Australianism

I was using a local apt mirror for testing that was not intended to be
committed.

Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/qemu-build.sh b/qemu-build.sh
index d95480a..a80d4e7 100755
--- a/qemu-build.sh
+++ b/qemu-build.sh
@@ -22,10 +22,6 @@
 
 ${PROXY}
 
-RUN echo "deb http://au.archive.ubuntu.com/ubuntu/ xenial main" > \
-    /etc/apt/sources.list
-
-
 ENV DEBIAN_FRONTEND noninteractive
 RUN apt-get update && apt-get install -yy --no-install-recommends \
 	flex bison \
@@ -34,7 +30,6 @@
 	libfdt-dev \
 	make python-yaml gcc libc6-dev
 
-
 RUN grep -q ${GROUPS} /etc/group || groupadd -g ${GROUPS} ${USER}
 RUN grep -q ${UID} /etc/passwd || useradd -d ${HOME} -m -u ${UID} -g ${GROUPS} ${USER}