toolbox: Make reboot a separate command from toolbox

Set the CAP_SYS_BOOT filesystem capability on the new reboot
command and keep CAP_SYS_BOOT in adb bounding set so that the
shell user can run it.

Change-Id: I1dd6143445ee2a952254f0452ab6e544318431dd
diff --git a/adb/adb.c b/adb/adb.c
index d2a2d27..93a9334 100644
--- a/adb/adb.c
+++ b/adb/adb.c
@@ -1195,8 +1195,9 @@
 #endif
     int i;
     for (i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) {
-        if ((i == CAP_SETUID) || (i == CAP_SETGID)) {
+        if (i == CAP_SETUID || i == CAP_SETGID || i == CAP_SYS_BOOT) {
             // CAP_SETUID CAP_SETGID needed by /system/bin/run-as
+            // CAP_SYS_BOOT          needed by /system/bin/reboot
             continue;
         }
         int err = prctl(PR_CAPBSET_DROP, i, 0, 0, 0);