Use llvm::Triple::isArch64Bit (LLVM 3.1+).
Don't require -triple when using -march.

There is really no reason we should, and I couldn't find out
why that check was added back in 2009.

Also cleaned up the code a bit now that the LLVM 3.0 branches
are gone.
Disentangle -march and -mcpu.

-mcpu=native now actually works.

GitHub: Fixes #414.
getX86TargetCPU cleanup.
Auto-detect target attributes for -mcpu=native.

This is currently only implemented for ARM in LLVM.
CPU detection for ARM.

This is not perfect yet, as lookupTarget wipes out any more
specific arch info (e.g. armv8) the triple might have.
Log/error message prettification.
if chain -> switch.
Add -float-abi switch and auto-detection for ARM.

This is based on the implementation that was reverted in
fc8e0c4c20f12f0f727063f0d63dae6d318999df.
Simplify FindLibconfig++ using find_package_handle_standard_args features.
ARM: Fold in druntime fixes.
Implement lookupTarget() with arch override for LLVM 3.1.

To be removed again once we drop 3.1 support.
Finally fix LLVM 3.1 compilation.
ARM: Use -arm-enable-ehabi(-descriptors).

D exception handling does not work at all yet, but with these
flags it does for C++/Clang, at least in simple cases.
Merge pull request #488 from klickverbot/arm

Phobos "Hello World" compiles now on ARM.

No EH support yet.