Fix synchronization when preparing ids.

Synchronized blocks were using different locks.
Replaced by a safer version: marking intern method synchronized.
This means synchronizing more than necessary but it had no
mesurable perfomance impact.

Bug 11744785

Change-Id: I35e691232cd6971d13735be9b72969739ef71e09
Retry mount() if it fails with EINTR

mount() may fail EINTR, and when it does this causes dalvik to crash.
Use the regular retry macro to avoid these problems.

Change-Id: I436fe4f0fab36c8172b43b8b9caedcb6d8167a4f