Add nvram user.

This is intended to be used by user space daemons that are part of
access-controlled NVRAM HAL implementations for Brillo. Because there
might be sensitive data flowing through the daemon, we'd like to run
it as a separate user.

BUG: 27764637
Change-Id: If6ad7923af3c650963ee9e926f732001b6a8cb5d

include/private/android_filesystem_config.h

@@ -91,6 +91,7 @@
 #define AID_CAMERASERVER  1047  /* cameraserver process */
 #define AID_FIREWALL      1048  /* firewalld process */
 #define AID_TRUNKS        1049  /* trunksd process (TPM daemon) */
+#define AID_NVRAM         1050  /* Access-controlled NVRAM */
 /* Changes to this file must be made in AOSP, *not* in internal branches. */
 
 #define AID_SHELL         2000  /* adb and debug shell user */
@@ -201,6 +202,7 @@ static const struct android_id_info android_ids[] = {
     { "cameraserver",  AID_CAMERASERVER, },
     { "firewall",      AID_FIREWALL, },
     { "trunks",        AID_TRUNKS, },
+    { "nvram",         AID_NVRAM, },
 
     { "shell",         AID_SHELL, },
     { "cache",         AID_CACHE, },