RFR(L) 8055494: Add C2 x86 intrinsic for BigInteger::multiplyToLen() method

[Roland Westrelin]

> https://bugs.openjdk.java.net/browse/JDK-8055494

In vm_version_x86.cpp, shouldn’t that be "multiplyToLen intrinsic is not available in 32-bit VM” rather than "not available in Client 32-bit VM"?

Anyway, That looks good to me.

Roland.