[16] RFR(M) 8251459: Compute caller save exclusion RegMasks once

[Vladimir Kozlov]

https://cr.openjdk.java.net/~kvn/8251459/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8251459

Claes once again found optimization for C2 code!

Instead of per bit exclusion SOC and AS registers from debuginfo regmasks he suggested to calculate exclusion masks once 
in Matcher::init_spill_mask() during first compilation and use these masks to do per word exclusion.
We can save 27k instructions per compilation on x64 with this!

I modified Claes's original patch by removing refactoring code to see changes more clear.

Tested: hs-tier1-3, xcomp

Thanks,
Vladimir