build: add support for eng userimages

build.sh

@@ -19,6 +19,7 @@ usage: $0 [-hn] [bootimage|bacon|clean|prune]
 flags:
     -h              show this help
     -n		    don't sync
+    -e 		    build an eng image
 
 commands:
     bootimage       build boot.img (kernel + dt.img + ramdisk, fast gate)
@@ -56,7 +57,13 @@ do_build() {
 
     set +eu
     source build/envsetup.sh
-    lunch lineage_rubenslte-userdebug
+
+    if [ -v "ENG_IMG" ]; then
+	lunch lineage_rubenslte-eng
+    else
+	lunch lineage_rubenslte-userdebug
+    fi
+    
     set -e
 
     if [ -z "${TARGET_PRODUCT:-}" ]; then
@@ -75,10 +82,11 @@ do_build() {
     rlte_ok "Done."
 }
 
-while getopts ":hn" opt; do
+while getopts ":hnd" opt; do
     case "$opt" in
         h) usage; exit 0 ;;
 	n) NO_SYNC=1 ;;
+	e) ENG_IMG=1 ;;
         *) usage; exit 1 ;;
     esac
 done