Performance improvement on writing a large index

Performance improvement on writing a large index

The index header consists of a 4-byte version number. The current
supported version numbers are 2 and 3. The code checks if any entries
are extended. If it finds any entries that are extended it picks version
'3', otherwise it chooses version '2'.

DirCache.java
-Changed the 'extended' check to exit early when any entry is considered
'extended' in the index.

(Of course, I maybe missing a bitwise optimization that is made in
the Java bytecode.)

Change-Id: If70db9454befe683319b974ebd3774060be9445d
Signed-off-by: Stephen Lawson <slawson@ptc.com>