zBarrierSetAssembler_x86.cpp doesn't compile when C1 is disabled. Also
JDK-8207965 introduced uses of COMPILER{1,2}_PRESENT macros in
ZBarrierSet, which instead should be solved with forward declarations.
Bug: https://bugs.openjdk.java.net/browse/JDK-8209883
Webrev: http://cr.openjdk.java.net/~pliden/8209883/webrev.0
/Per