GameScope: change argument building logic

Previously we used 'mapfile', which we can't use now because
some arguments may have spaces in their path.

We use new logic now using readarray and some sed magic to
break up the gamescope arguments and build each argument and its value
separately.

steamtinkerlaunch

@@ -6,7 +6,7 @@
 PREFIX="/usr"
 PROGNAME="SteamTinkerLaunch"
 NICEPROGNAME="Steam Tinker Launch"
-PROGVERS="v12.12.20230217-1"
+PROGVERS="v12.12.20230217-4"
 PROGCMD="${0##*/}"
 SHOSTL="stl"
 GHURL="https://github.com"
@@ -17957,7 +17957,11 @@ function gameScopeArgs {
 	unset GAMESCOPEARGSARR
 
 	if [ "$1" != "$NON" ]; then
-		mapfile -d " " -t -O "${#GAMESCOPEARGSARR[@]}" GAMESCOPEARGSARR < <(printf '%s' "$ARGSTRING")
+		GSINARGS="$( echo "$ARGSTRING" | sed "s:--:\n--:g;s:\ -:\n-:g;s:\ ':\n':g" )"  # Turn incoming GameScope arguments into newline
+		readarray GSINARR<<< "$GSINARGS"
+		for GSARG in "${GSINARR[@]}"; do
+			GAMESCOPEARGSARR+=("$( echo "$GSARG" | xargs )")
+		done
 	fi
 
 	if [ "${#GAMESCOPEARGSARR[@]}" -ge 1 ]; then