RFR: Extend substitution guards to receive Architecture

[Igor Veresov]

- adds ability for substitution guards to have a constructor that has Architecture as an argument
- added extra flags enum to AMD64 to drive code emission features (currently contains UseCountLeadingZerosInstruction and UseCountTrailingZerosInstruction)
- moved lzcnt/tzcnt nodes and substitutions to com.oracle.graal.replacements.amd64

Webrev: http://cr.openjdk.java.net/~iveresov/subst-guard/webrev.00/

Thanks!
igor