extract_utils: Seperate multiple override targets with comma

This follows the style google uses, for example in [1].

With this change it will generate 'overrides: ["TargetOne", "TargetTwo"],'
instead of 'overrides: ["TargetOne TargetTwo"],' for this line:
-system/app/TargetZero/TargetZero.apk;OVERRIDES=TargetOne,TargetTwo

[1]: https://github.com/LineageOS/android_packages_apps_CellBroadcastReceiver/blob/2daf3ecf897c35725c8ae78f7fd6533773a8bf50/Android.bp#L53

Change-Id: I154ee3a4cc51e0938c860dcfc125eacf279d102e
diff --git a/build/tools/extract_utils.sh b/build/tools/extract_utils.sh
index 8edb0df..976b2e8 100755
--- a/build/tools/extract_utils.sh
+++ b/build/tools/extract_utils.sh
@@ -430,7 +430,7 @@
                     printf '\tpresigned: true,\n'
                 elif [[ "$ARG" =~ "OVERRIDES" ]]; then
                     OVERRIDEPKG=${ARG#*=}
-                    OVERRIDEPKG=${OVERRIDEPKG//,/ }
+                    OVERRIDEPKG=${OVERRIDEPKG//,/\", \"}
                     printf '\toverrides: ["%s"],\n' "$OVERRIDEPKG"
                 elif [ ! -z "$ARG" ]; then
                     USE_PLATFORM_CERTIFICATE="false"