sstate/bitbake.conf: Use pigz if available

Currently the compression of sstate objects is single threaded. In the case
of ltp, this takes around 33s. If we add pigz into the list of non-fatal
HOSTTOOLS and then use if it available when building the sstate object,
this time drops to around 6s.

Since pigz is now widely available this is an optimisation we should
utilise.

(From OE-Core rev: 2de56aa0792ec93445130d801936a8ea643fad27)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/sstate.bbclass

@@ -715,17 +715,24 @@ sstate_task_postfunc[dirs] = "${WORKDIR}"
 #
 sstate_create_package () {
 	TFILE=`mktemp ${SSTATE_PKG}.XXXXXXXX`
+
+        # Use pigz if available
+        OPT="-cz"
+        if [ -x "$(command -v pigz)" ]; then
+            OPT="-I pigz -c"
+        fi
+
 	# Need to handle empty directories
 	if [ "$(ls -A)" ]; then
 		set +e
-		tar -czf $TFILE *
+		tar $OPT -f $TFILE *
 		ret=$?
 		if [ $ret -ne 0 ] && [ $ret -ne 1 ]; then
 			exit 1
 		fi
 		set -e
 	else
-		tar -cz --file=$TFILE --files-from=/dev/null
+		tar $OPT --file=$TFILE --files-from=/dev/null
 	fi
 	chmod 0664 $TFILE
 	mv -f $TFILE ${SSTATE_PKG}

meta/conf/bitbake.conf

@@ -490,7 +490,7 @@ HOSTTOOLS += " \
 HOSTTOOLS += "${@'ip ping ps scp ssh stty' if (bb.utils.contains_any('IMAGE_CLASSES', 'testimage testsdk', True, False, d) or any(x in (d.getVar("BBINCLUDED") or "") for x in ["testimage.bbclass", "testsdk.bbclass"])) else ''}"
 
 # Link to these if present
-HOSTTOOLS_NONFATAL += "aws ccache gcc-ar gpg ld.bfd ld.gold nc sftp socat ssh sudo"
+HOSTTOOLS_NONFATAL += "aws ccache gcc-ar gpg ld.bfd ld.gold nc pigz sftp socat ssh sudo"
 
 # Temporary add few more detected in bitbake world
 HOSTTOOLS_NONFATAL += "join nl size yes zcat"