Updated the runtest script to build libtangobos-partial.a if it hasn't already been built.
Added in signbit() and va_arg!()() to libtangobos-partial.a so more of the phobos dependent DStress tests pass.
Added: started support for x86 80bit floating point.
Changed: aggregates passed by value now use the llvm 'byval' parameter attribute, also lays ground work for
using other attributes.
Changed: eliminated a lot more std::vectorS, these showed up pretty much at the top when profiling!
Changed: performed other misc. cleanups.
Changed: halt expression now call the new llvm trap intrinsic instead of an assert(0).
Changed: dstress suite now passes -O0 by default, this only eliminates unreferenced globals, which speeds up
linking quite a bit.
