hotspot 'jdk6_or_earlier logic' for FDS needs to be removed

This issue came up during the code review cycle for JDK-7165611. The comment
below is for the BSD/MacOS X Makefiles, but the 'jdk6_or_earlier logic' also exists
for other platforms.

> - make/bsd/makefiles/defs.make
>
> Note that the whole jdk6_or_earlier logic is defunct as this will never be used for jdk6 or earlier. But best to clean all that up at the one time.

Agreed that we (Oracle) currently don't have plans to drop HSX-25 into
JDK6 or OpenJDK6, but I don't want to rule out future insanity.

Also agreed that cleaning up that logic should all be done at the same
time using a different bug ID.