One more data point:
My gcc is
gcc -v
Reading specs from /usr/local/lib/gcc/sparc-sun-solaris2.8/3.4.3/specs
Configured with: ../configure --enable-threads=posix --enable-languages=c++
--disable-nls : (reconfigured) ../configure --enable-threads=posix
--disable-nls --enable-languages=c++ :
(reconfigured) ../configure --enable-threads=posix --disable-nls
--enable-languages=c++
Thread model: posix
gcc version 3.4.3