clang/llvm based toolchain for ARM

[Abdoulaye Walsimou GAYE]

Hello,
For those wanting to experiment with a clang/llvm based toolchain
as a drop in replacement of the traditional GCC based toolchain,
EmbToolkit as of v1.1.0 provides this.

Of course uClibc (even less eglibc) does not compile with clang/llvm toolchain, so it is compiled
with a second stage gcc (which still provides the compiler runtime interface with its libgcc).
The c++ standard library also comes from gcc with its libstdc++, but the goal is to replace it
for the coming releases with libc++ from llvm project (just as FreeBSD recently).

Busybox compiles and works fine, but with the help of some patches: removing a nested function,
working around some global const ptr and replacing ash evaltreenr function alias of evaltree
with a function calling evaltree followed by a call of __builtin_unreachable();

As said in the subject, this is only available for ARM, while MIPS support is planed for the next release.

à la votre,
AWG