[D-runtime] Time for druntime for Linux64 to default to a shared lib

[Jonathan M Davis]

On Wednesday, March 13, 2013 00:01:05 Walter Bright wrote:
> Therefore, it's now time to make this now the default. This requires some
> changes to the makefiles for druntime, phobos, and some tweaks to dmd.

I'd like to point out that one place that we probably _won't_ want to use 
druntime as shared is dmd (once it's been ported to D), as I believe that 
doing so would mean that we'd have to recompile dmd after compiling druntime 
(as well as worry about making sure that dmd ran with the old copy of druntime 
until it had been compiled with the new one) - either that or dmd would have 
to have its own copy of the druntime shared lib (as the newly compiled 
druntime would not necessarily be compatible with the old one; this would be 
particularly bad on Windows due to how picky the dll linking scheme is in 
comparison to the so linking scheme). It would just be simpler for dmd to link 
against druntime statically.

- Jonathan M Davis