initscripts: populate-volatile.sh: run create_file synchronously

The behavior of running create_file in the background was introduced in
d44816bedade ("initscripts: Populate volatile from existing file")
without further explanation. Besides its questionable benefit, this
causes actual issues:

- Not all create_file processes may have finished by the time the
  initscript exits (or when it moves /etc/volatile.cache.build !)
- By making the order of commands nondeterminstic, it could hide
  dependency issues where it was attempted to create files before their
  containing directories

(From OE-Core rev: 1a4ddb0d3f1289e0b67b6eba9be58374d3d7a80b)

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/initscripts/initscripts-1.0/populate-volatile.sh

@@ -201,7 +201,7 @@ apply_cfgfile() {
 			"f")  [ "${VERBOSE}" != "no" ] && echo "Creating file -${TNAME}-."
 				TSOURCE="$TLTARGET"
 				[ "${TSOURCE}" = "none" ] && TSOURCE=""
-				create_file "${TNAME}" "${TSOURCE}" &
+				create_file "${TNAME}" "${TSOURCE}"
 				;;
 			"d")  [ "${VERBOSE}" != "no" ] && echo "Creating directory -${TNAME}-."
 				mk_dir "${TNAME}"