RFR(S): 8055055: Improve numeric parsing in java.sql

[Claes Redestad]

Hi,

can I have a review of this small patch which improves performance of 
java.sql.Time::valueOf (~1.3x) and java.sql.Timestamp::valueOf (~1.9x).

Uses Integer.parseInt with offset to make intermediary substrings 
unnecessary and improves the nanosecond fraction calculation to not use 
String concatenation.

bug: https://bugs.openjdk.java.net/browse/JDK-8055055
webrev: http://cr.openjdk.java.net/~redestad/8055055/webrev.0/

Thanks!

/Claes