Allocate GID to use reserved disk space.

Filesystems like ext4 allow the setting of the "resgid" parameter
to designate a GID that is allowed to use the "reserved" disk space
(in addition to UID 0).  We'll be granting this GID to critical
system processes, so that the system is usable enough for the user
to free up disk space used by apps.

Test: builds
Bug: 36450358
Change-Id: I224bd1e597130edb411a1528872faff1ada02a89
diff --git a/libcutils/include/private/android_filesystem_config.h b/libcutils/include/private/android_filesystem_config.h
index 0037f15..3eeb9dc 100644
--- a/libcutils/include/private/android_filesystem_config.h
+++ b/libcutils/include/private/android_filesystem_config.h
@@ -130,6 +130,7 @@
 #define AID_MEDIA_OBB 1059       /* GID for OBB files on internal media storage */
 #define AID_ESE 1060             /* embedded secure element (eSE) subsystem */
 #define AID_OTA_UPDATE 1061      /* resource tracking UID for OTA updates */
+#define AID_DISK_RESERVED 1062   /* GID that has access to reserved disk space */
 /* Changes to this file must be made in AOSP, *not* in internal branches. */
 
 #define AID_SHELL 2000 /* adb and debug shell user */