Load default prop from /system/etc/prop.default

/default.prop is moved to /system/etc/prop.default for full Treblized
devices. Modifies property_service to load it from there first.
In recovery mode, the file is renamed as /prop.default. This path is
tried if /system/etc/prop.default is not available.

Bug: 37815285
Test: Tested with ag/2419001. Booted pixel phones, checked the location
      of prop.default, verified the symlink at /default.prop, checked a
      few properties via adb shell and manually tested a few apps.
      Booted to recovery and ran 'adb sideload' successfully.
Change-Id: I485231f21fc86b0aec58edf867e229a31e77d85e
diff --git a/libcutils/fs_config.cpp b/libcutils/fs_config.cpp
index 221dea2..c39071c 100644
--- a/libcutils/fs_config.cpp
+++ b/libcutils/fs_config.cpp
@@ -134,7 +134,8 @@
     { 00640, AID_ROOT,      AID_SHELL,     0, "data/nativetest64/tests.txt" },
     { 00750, AID_ROOT,      AID_SHELL,     0, "data/nativetest/*" },
     { 00750, AID_ROOT,      AID_SHELL,     0, "data/nativetest64/*" },
-    { 00600, AID_ROOT,      AID_ROOT,      0, "default.prop" },
+    { 00600, AID_ROOT,      AID_ROOT,      0, "default.prop" }, // legacy
+    { 00600, AID_ROOT,      AID_ROOT,      0, "system/etc/prop.default" },
     { 00600, AID_ROOT,      AID_ROOT,      0, "odm/build.prop" },
     { 00600, AID_ROOT,      AID_ROOT,      0, "odm/default.prop" },
     { 00444, AID_ROOT,      AID_ROOT,      0, odm_conf_dir + 1 },