MT-safe exception and thread library

[Teemu Torma]

    From:  hjl@lucon.org (H.J. Lu)
    Date:  Tue, 16 Dec 1997 11:29:29 -0800 (PST)

    I am not sure if I like the multilibs for the Thread-safe EH support.
    That may be a problem for glibc. I'd like to see an option for a
    single libgcc.a with the the Thread-safe EH support using weak
    symols. I think it should work with gcc on platforms with weak
    support. We can use SUPPORTS_WEAK to detect it. It should be
    very easy to do.
    
It is not nice to use multilibs, but I am not sure if using weak
symbols is that straightforward.  One problem that may arise is
that MT code should usually be compiled with some preprocessor
options (-D_REENTRANT for example), which also changes some other 
things, at least how "errno" is defined.  It may or may not cause
problems in libgcc.

Teemu