More embarrassing microbenchmars for D's GC.

[Rounin]

Thank you for that advice. I'm using GDC because it's available from Ubuntu
Linux's package system, whereas DMD currently is not. (And the .deb posted on
digitalmars.com is only for i386.) Hopefully, D will gain more popularity and more
up-to-date tools will be made available.

By the way, today I re-compiled the program with a "std.gc.enable;" right before
the final "return 0" statement, and it still runs in 0.68 seconds. So either those
objects aren't marked as needing garbage collection, or it's really just an issue
of keeping the garbage collector from activating too quickly.