[OE-core] how to pass or set specific gcc flags?

[Kumar Gala]

We'd like to pass:

--enable-targets=all

on ppc when we target a 64-bit platform but happen to build a 32-bit toolchain & rootfs, its useful to still have 64-bit support in the compiler to build a 64-bit kernel if desired in this scenario.  Also, this seems useful for the multilib situation.

Wondering what the best way of doing this.  Adding something into the tune-ppcFOOBAR file but not sure how to do that so it gets picked up by the right toolchain pass.  And what do we even override?  I suggested adding a GCC_EXTRA_OECONF.

- k