RFR(L) 8026844: Various Math functions needs intrinsification

[Rickard Bäckman]

Hi, can I get reviews for the following change:

This change creates intrinsics for addExact(long, long), subtractExact,
negateExact, incrementExact, decrementExact and multiplyExact.

The intrinsics are only added on x86 and only 64-bit has the intrinsics
for the long-versions. (32-bit only has int-versions).

Bug: https://bugs.openjdk.java.net/browse/JDK-8026844
Webrev: http://cr.openjdk.java.net/~rbackman/8026844/

Thanks
/R