SHORT SUMMARY: Improve getTimeZone performance
INDICATORS: Slow IO possible on some windows boxes while indexing through and 
creating
a Map of all available TimeZones in JRE.
COUNTER INDICATORS:
TRIGGERS: 
JDeveloper team have reported a temporary GUI hang while dispatching a 
TimeZone intensive IO operation
on their awt event dispatch thread. Suggested they don't perform IO on EDT 
but not accepted.
KNOWN WORKAROUND: Never put intensive IO operation on EDT
PRESENT SINCE: N/A
HOW TO VERIFY: JDeveloper team are happy with recent proposed changes.
In local tests, I've see time for testcase (available in bugDB 13511596) fall 
from ~4 seconds to 3 seconds on windows box
NOTES FOR SE: Request to port to 6uX and later releases.
Changes involve reducing the number of file stats performed on files in 
jre/zi directory and add an alias look-up table to avoid reading TZ aliases 
where possible.
REGRESSION: No.