Apply static RRO

Static RRO package is designed to support resource overlay for system
server and they shouldn't be disabled or changed by a user.
The design details are in go/treble-static-rro.

Selection method for static RROs will be applied later when its design
is determined.

Test: building succeeded and tested on sailfish.
Bug: 35742444
Change-Id: I8cbf2fd37a73a24bf6ad291e2c5cf75a0fc757fc
diff --git a/cmds/idmap/idmap.cpp b/cmds/idmap/idmap.cpp
index 3ab1915..3a237ff 100644
--- a/cmds/idmap/idmap.cpp
+++ b/cmds/idmap/idmap.cpp
@@ -49,8 +49,8 @@
       --path: create idmap for target package 'target' (path to apk) and overlay package \n\
               'overlay' (path to apk); write results to 'idmap' (path). \n\
 \n\
-      --scan: non-recursively search directory 'dir-to-scan' (path) for overlay packages with \n\
-              target package 'target-package-name-to-look-for' (package name) present at\n\
+      --scan: non-recursively search directory 'dir-to-scan' (path) for static overlay packages \n\
+              with target package 'target-package-name-to-look-for' (package name) present at\n\
               'path-to-target-apk' (path to apk). For each overlay package found, create an\n\
               idmap file in 'dir-to-hold-idmaps' (path). \n\
 \n\