PDF-625 updated inputStream lock/releae with a reenterant lock.

git-svn-id: http://anonsvn.icesoft.org/repo/icepdf/trunk/icepdf@37287 1de00972-ac04-4911-a46b-06793c8d78d9
PDF-625 synchronized the init method so that it could be properly initialized when accessed from multiple threads.

git-svn-id: http://anonsvn.icesoft.org/repo/icepdf/trunk/icepdf@37288 1de00972-ac04-4911-a46b-06793c8d78d9