RFR (S): 8140091: remove VMStructs cast_uint64_t workaround for GCC 4.1.1 bug

[Christian Thalinger]

https://bugs.openjdk.java.net/browse/JDK-8140091
http://cr.openjdk.java.net/~twisti/8140091/webrev/

There is a bit more context in JIRA but the bottom line is that we shouldn’t be building the JDK with GCC 4.1.1.  We have a workaround in just one place but that doesn’t mean the bug doesn’t show up in other places (especially new code).

I’m suggesting to remove the workaround and blacklist this particular GCC version.