RFR(S): 7066841: remove MacroAssembler::br_on_reg_cond() on sparc

[John Cuthbertson]

Hi Everyone,

Can I have couple of volunteers look over these changes? The webrev can 
be found at: http://cr.openjdk.java.net/~johnc/7066841/webrev.0/.

These changes basically remove the macro assembler routine 
br_on_reg_cond and replace the remaining calls to that routine, in the 
G1 barriers, with an equivalent.

Testing: GC test suite and Kitchensink on 32/64 bit sparc with -Xint, 
-client -Xcomp, -XX:+TieredCompilation -XX:TieredStopAtLevel=1, and 
default. VerifyDuringGC and VerifyBeforeGC were also enabled to detect 
missing barriers.

Thanks,

JohnC