build update

Focusing currently on latest GCC archive release builds.

Fixed a bug in the 32-bit DWCAS code for GCC >= 4.1.2 and 4.7.3.

Now what I’m left with is that test goes badly wrong on i686 with 4.5.4 and 4.6.4 and on mips with 4.5.4 (but 4.6.4 on mips is fine).

Later compilers work. I don’t have versions so far back except on x86_64, which I’ve not tried yet – so those compilers currently are only for those platforms.

The problem seems to be that DWCAS goes wrong.

Investigation continues.