libgcc c++ support bits moved

[Hans-Peter Nilsson]

> Date: Mon, 9 Oct 2000 14:20:31 -0700
> From: Richard Henderson <rth@cygnus.com>

> gcc/
>         * mklibgcc.in: Remove LIB2ADD .txt processing.

Oh please pretty please add it back.

Targets that need to add multilibbed files to libgcc2 can
otherwise not compile those files with options other than for
the rest of libgcc2 (without severe tearing of hair and override
of libgcc.mk, I guess).  The .txt processing added the
proverbial indirection through which this was feasible.
*Sigh* I'll do my very best to get that target in, so the .txt
feature is actually used...

Or if there's another solution to this, I'm all ears.

brgds, H-P