thread-safety flag on Solaris 10

Hello -

We are installing Postgresql-9.1.3 from source against solaris 10, gcc
3.4.6 and it is fails when I enable thread-safety flag.
It install fine if I disable thread-safety flag. One of the options I am
looking into is upgrading gcc. Upgrading Solaris is not an option.
But before I do that, I would like to know the consequences of
installing pg without thread-safety. We do not use Slony, which I have
heard can break if I disabled thread-safety flag.
We use pgadmin, Java/jdbc to access postgres.

Here is the machine specs:

# uname -X
System = SunOS
Node = sierra-db.toledolibrary.org
Release = 5.10
KernelID = Generic_147440-23
Machine = sun4v
BusType = <unknown>
Serial = <unknown>
Users = <unknown>
OEM# = 0
Origin# = 1
NumCPU = 128

gcc version = 3.4.6
Thread model = posix

Please let me know.

Thanks.
Dinesh