GSSAPI on Solaris - psql segfault

I just took a look at adding gssapi build support on solaris (solaris
10/x86_64, sun studio 10, 64bit build) which seemed easy enough by
educating configure to look for -lgss but while it compiles just fine
the resulting tree will not be able to complete a make check due to
psql(!) segfaulting as soon as it tries to connect to the backend.

the backtrace looks similiar to:

program terminated by signal SEGV (no mapping at the fault address)
0x00007fffffd3d401: _memcpy+0x00e1: movq %rax,(%rdi)
Current function is pqPutMsgBytes
475 memcpy(conn->outBuffer + conn->outMsgEnd, buf, len);
(dbx) where
[1] _memcpy(0x4, 0x4709a0, 0x67, 0x2, 0x646c697562677000,
0x7361626174616400), at 0x7fffffd3d401
=>[2] pqPutMsgBytes(buf = 0x4709a0, len = 103U, conn = 0x4682f0), line
475 in "fe-misc.c"
[3] pqPutnchar(s = 0x4709a0 "", len = 103U, conn = 0x4682f0), line 189
in "fe-misc.c"
[4] pqPacketSend(conn = 0x4682f0, pack_type = '\0', buf = 0x4709a0,
buf_len = 103U), line 2439 in "fe-connect.c"
[5] PQconnectPoll(conn = 0x4682f0), line 1299 in "fe-connect.c"
[6] connectDBComplete(conn = 0x4682f0), line 936 in "fe-connect.c"
[7] PQsetdbLogin(pghost = (nil), pgport = (nil), pgoptions = (nil),
pgtty = (nil), dbName = 0xfffffd7fffdffbeb "postgres", login = (nil),
pwd = (nil)), line 660 in "fe-connect.c"
[8] main(argc = 3, argv = 0xfffffd7fffdff9b8), line 211 in "startup.c"

ideas ?

Stefan