dist/debian: requires root privilege to wipe build directory

Since we run pbuilder as root, .deb packages owned by root user so we need to
run 'rm -rf build' as root as well.

Signed-off-by: Takuya ASADA <syuu@scylladb.com>
Message-Id: <1512373941-7018-1-git-send-email-syuu@scylladb.com>
(cherry picked from commit 0f38eb221e)

dist/debian/build_deb.sh

@@ -48,7 +48,7 @@ if [ "$(arch)" != "x86_64" ]; then
 fi
 
 if [ -e debian ] || [ -e build/release ]; then
-    rm -rf debian build
+    sudo rm -rf debian build
     mkdir build
 fi
 if is_debian_variant; then