RFR: 8220420: Cleanup c1_LinearScan

[Claes Redestad]

Hi,

please review this small optimization and cleanup of c1_LinearScan.

Webrev: http://cr.openjdk.java.net/~redestad/8220420/open.00/
Bug:    https://bugs.openjdk.java.net/browse/JDK-8220420

Testing: tier1-3

/Claes