[yocto] clang cross compiler for OE available in meta-clang

[Khem Raj]

Hi All,

Finally, clang/llvm is now in a working state as a cross compiler in meta-clang layer

https://github.com/kraj/meta-clang

Currently, It will build clang and stage it along with gcc cross compilers, default remains
as it is. If you wish to compile an additional recipe using clang you will add following two entries per recipe


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

to conf/clang.conf 

and it will start using clang for that component. Right now it only has one entry for ‘lzo’ :)
I am hoping to have this list grow soon

Right now, its only the cross compiler, which means compiler runtime is still same from gcc
and binutils are used in same way

Eventually, I will add compiler-rt and libc++ as well and also add cross-canadian builds of clang and make it cohabit in SDK
along with gcc.

If you would like to help trying/porting recipes to use clang/llvm or improve the layer, please lend your hand

Thanks for your time

-Khem