darwin, symbol visibility differences between libgcc_s and libgcc

[IainS]

Hi,

I've noticed that there are a few symbols that appear " T " from  
libgcc.a and " t " from libgcc_s.1.dylib.
(the exact set depends on ppc/intel and 32/64)
for example, on darwin9 (32 bit libs) the following;
___copysigntf3
___fabstf2
___udiv_w_sdiv
___unordtf2

Is there some specific reason it's done this way?
Iain