These are not part of target image and many of these tools are still
not ported to be buildable with clang, so lets use gcc for building them
at this moment

Signed-off-by: Khem Raj <raj.khem@gmail.com>

The option is not defined for llvm/clang but the defaults are hard-float
anyway so not needed

Signed-off-by: Khem Raj <raj.khem@gmail.com>

Signed-off-by: Khem Raj <raj.khem@gmail.com>

So far we have been selecting which packages are compiled using clang
this patch changes the logic to use clang by default unless selecting

TOOLCHAIN = "gcc"

explicitly in the recipe

We have not yet enabled clang for native recipes, its only enabled for
target recipes needing cross compilation as of now.

Get rid of configuration file and move the code to clang.bbclass,
simplifies the logic

If needed to select gcc to be default system compiler set

TOOLCHAIN = "gcc" in local.conf

Signed-off-by: Khem Raj <raj.khem@gmail.com>

We add clang as an alternative compiler, it sitll uses underlying
binutils and compiler runtime, it will only do the compilation and defer
link, to GNU ld/gold, to compile a component usign clang add

TOOLCHAIN_pn-<recipe-name> = "clang"
DEPENDS_append_pn-<recipe-name> = " clang-cross "

And OE will start using clang to compile <recipe-name>

Signed-off-by: Khem Raj <raj.khem@gmail.com>