RFR(XS): Assembler::bsrl fails on assert when -UseCountLeadingZerosInstruction is used on CPU with LZCNT support

[Igor Veresov]

We have an assert here that is too strong. The problem the assert tries to guard agaist is that on x86 a bsr instruction with an f3 prefix (rep), is actually an lzcnt instruction on CPUs that support it. Actually we never do emit bsr with rep, but I relaxed that assert to verify that, just in case.

JBS: https://bugs.openjdk.java.net/browse/JDK-8038222
Webrev: http://cr.openjdk.java.net/~iveresov/8038222/webrev.00/


Thanks!
igor