Move reboot() from common.h into otautil/sysutil.h.

This breaks the dependency on common.h (which belongs to
recovery/librecovery) from librecovery_ui. reboot() is now owned by
libotautil, which is expected to be a leaf node to be depended on.

With the change, recovery and updater also share the same reboot() code
now.

Test: mmma -j bootable/recovery
Change-Id: I1cc5d702cfe49302048db33d31c9c87ddc97ac71
diff --git a/otautil/Android.bp b/otautil/Android.bp
index 0be019c..b058f7b 100644
--- a/otautil/Android.bp
+++ b/otautil/Android.bp
@@ -48,6 +48,7 @@
 
             static_libs: [
                 "libselinux",
+                "libcutils",
             ],
         },
     },