Move /default.prop to /system/etc/prop.default

This patch tries to fix the problem where the default properties need
to go with the system image especially on non-AB devices where
/default.prop is on the ramdisk image. A symlink is created at
/default.prop for backward compatibility.

Bug: 37815285
Test: Tested with ag/2416542. Booted pixel phones, checked the location
      of prop.default, verified the symlink, checked a few properties
      (via adb shell getprop) and manually tested a few apps (Camera,
      Maps etc).
      sign_target_files_apks.py was tested with:
      sign_target_files_apks -o -e DynamiteLoader.apk= -e DynamiteModulesA.apk= \
          -e DynamiteModulesB.apk= -e DynamiteModulesC.apk= -e DynamiteModulesD.apk= \
          -e GoogleCertificates.apk= out/dist/*-target_files-*.zip signed-target_files.zip
      Booted to recovery and ran 'adb sideload' successfully.
Change-Id: I1a9a2ba49c8252afc13ced3dea71253afbd3091e
Merged-In: I1a9a2ba49c8252afc13ced3dea71253afbd3091e
(cherry-picked from 4fbbe4578bb10d54292d9b243edf4999fddf1c93)
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index c661333..8d251e2 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -212,11 +212,17 @@
     # System properties.
     elif info.filename in ("SYSTEM/build.prop",
                            "VENDOR/build.prop",
-                           "BOOT/RAMDISK/default.prop",
-                           "ROOT/default.prop",
-                           "RECOVERY/RAMDISK/default.prop"):
+                           "SYSTEM/etc/prop.default",
+                           "BOOT/RAMDISK/prop.default",
+                           "BOOT/RAMDISK/default.prop",  # legacy
+                           "ROOT/default.prop",  # legacy
+                           "RECOVERY/RAMDISK/prop.default",
+                           "RECOVERY/RAMDISK/default.prop"):  # legacy
       print "rewriting %s:" % (info.filename,)
-      new_data = RewriteProps(data, misc_info)
+      if stat.S_ISLNK(info.external_attr >> 16):
+        new_data = data
+      else:
+        new_data = RewriteProps(data, misc_info)
       common.ZipWriteStr(output_tf_zip, out_info, new_data)
 
     elif info.filename.endswith("mac_permissions.xml"):