Starting to prepare for LLVM 3.5 (as of current git).

Also preparing to bring lldb building back.

Includes a feature patch to enable the stackmap intrinsic on ELF.
More work for LLVM 3.5

Now using cmake for building libc++abi.

README still out of date. Darwin untested.
Latest libcxx can now link to in-tree libc++abi directly.

Also removing the stackmap patch, as it has been commited to trunk.
Adding stackmaps-for-ELF patch from upstream.

LLVM git revision ec9de4677ac61
Fixes for Darwin.

Includes mechanism to cherry-pick existing commits.
Cleanup.

Removing code that's no longer needed.
Removing support for libcxxrt.

libc++abi now seems to work fine on both Linux and Darwin, and it's
(mostly) integrated into the LLVM build system.
Fixing typo.

Note: doesn't compile on Linux anymore right now. Sigh.

/usr/bin/ld:
../../lib/libLLVMAArch64CodeGen.a(AArch64AsmPrinter.cpp.o): relocation
R_X86_64_32S against `.text' can not be used when making a shared
object; recompile with -fPIC
Fix for Linux.

This turns on building shared libraries.
Disabling stage 3 for now.

Now that we're building shared libraries, this doesn't quite work
anymore.
Linux fix now that we are compiling shared libraries.
Removing stage 3 and adding options to select build mode and assertions.
Hardcoding current libcxxabi.
Switching Darwin to shared libraries as well.
Updating README.
Merge branch 'llvm35'
README polishing.
Fixing bootstrapping with gcc.

Turns out it didn't work anymore to bootstrap with gcc because
that can't compile libc++abi. *sigh*.

Added a phase 0 that bootstraps a clang without using
libc++/libc++abi. That will then be used in phase 1 and 2. Phase zero
is skipped if (any) clang is available already.
Adding Dockerfile.

This builds an Ubuntu image with LLVM/clang installed into /opt/llvm.
Updating README.