test: Substitute GNU commands for other commands where available

We are simply checking for gnuCMD and gCMD for each command we
are interested in.

Gbp-Dch: ignore

test/integration/framework

@@ -31,7 +31,6 @@ if [ "${MSGCOLOR:-YES}" = 'YES' ]; then
 	fi
 fi
 
-
 if [ "$MSGCOLOR" != 'NO' ]; then
 	CERROR="\033[1;31m" # red
 	CWARNING="\033[1;33m" # yellow
@@ -276,8 +275,13 @@ find_project_binary_dir() {
 	fi
 }
 setupenvironment() {
+	# Next check needs a gnu stat, let's figure that out early.
+	stat=stat
+	if command -v gnustat >/dev/null 2>&1; then
+		stat=gnustat
+	fi
 	# privilege dropping and testing doesn't work if /tmp isn't world-writeable (as e.g. with libpam-tmpdir)
-	if [ -n "$TMPDIR" ] && [ "$(id -u)" = '0' ] && [ "$(stat --format '%a' "$TMPDIR")" != '1777' ]; then
+	if [ -n "$TMPDIR" ] && [ "$(id -u)" = '0' ] && [ "$($stat --format '%a' "$TMPDIR")" != '1777' ]; then
 		unset TMPDIR
 	fi
 	TMPWORKINGDIRECTORY="$(mktemp -d)"
@@ -290,6 +294,18 @@ setupenvironment() {
 	fi
 	msgninfo "Preparing environment for ${0##*/} in ${TMPWORKINGDIRECTORY}…"
 
+	# Setup coreutils on BSD systems
+	mkdir "${TMPWORKINGDIRECTORY}/bin"
+	for prefix in gnu g; do
+			for command in stat touch sed cp tr sha1sum sha256sum md5sum sha512sum grep date wc chmod head readlink tar expr base64; do
+					if command -v $prefix$command 2>/dev/null >/dev/null; then
+							[ -e "${TMPWORKINGDIRECTORY}/bin/$command" ] || ln -sf $(command -v $prefix$command)  "${TMPWORKINGDIRECTORY}/bin/$command"
+					fi
+			done
+	done
+	export PATH="${TMPWORKINGDIRECTORY}/bin/:$PATH"
+
+
 	mkdir -m 700 "${TMPWORKINGDIRECTORY}/downloaded"
 	if [ "$(id -u)" = '0' ]; then
 		# relax permissions so that running as root with user switching works