RFR [9] 8041972: Add improved parse/format methods for Long/Integer

Hi, please review this patch to add offset based variants of Integer.parseInt/parseUnsignedInt, Long.parseLong/parseUnsignedLong and expose them through JavaLangAccess along with formatUnsignedInt/-Long. This is proposed to enable a number of minor optimizations, starting with https://bugs.openjdk.java.net/browse/JDK-8006627 Webrev: http://cr.openjdk.java.net/~redestad/8041972/webrev.0/ Thanks! /Claes