[Ur] Compiling Ur/Web with Link-time optimization (WAS: Re: Patches to compile Ur/Web with clang)

[austin seipp]

I'll also go ahead and note that I'm willing to bet that LLVM-based
LTO (with bitcode) using the LLVM toolchain would likely yield similar
results, but it would likely involve significantly more build
infrastructure, hence my opting to use GCC's LTO support. :) So if
this garners interest (because we need to go *even faster*), it may be
worth adding support for both (because GCC LTO only supports Linux
right now, and furthermore gold is linux only - the LTO approach can
work anywhere with LLVM bitcode, however.)

-- 
Regards,
Austin