[oe] Standalone gcc library builds

[Richard Purdie]

Hi,

We currently build gcc and all its runtime libraries as part of at least
"gcc-cross", "gcc", "gcc-cross-sdk". Packaging of these libraries varies
between the different recipes and is a pretty scary place for things to
go wrong which I've frequently seen.

I'm working on the idea of having the above packages just generate the
compiler binaries (host tools) and having a "gcc-runtime" package which
builds all the libraries (target libs). I think can make this work
expect for libgcc itself which is proving a real pain (unsurprisingly).

For libgcc, we can save the bits it needs from the gcc build into
staging and then make it build that way, or just build it as a special
case as part of gcc, stash it in staging, then package it as part of
gcc-runtime.

Does anyone have any better ideas of experience of playing with libgcc?

Cheers,

Richard