Support QtConcurrent with Sun CC 5.9.

Additional information:

While Sun CC 5.9 is not currently supported, attempts at building QtConcurrent with CC 5.9 and stlport4 have been successful. However, running the map example resulted in a crash, with the following stack trace:

(dbx) run
Running: mapdemo
(process id 4147)
Reading libc_psr.so.1
t@1 (l@1) signal SEGV (no mapping at the fault address) in
QtConcurrent::ThreadEngineBase::startBlocking at 0xfe0fdb98
0xfe0fdb98: startBlocking+0x0010: ld [%i0], %i5
(dbx) where
current thread: t@1
=>[1] QtConcurrent::ThreadEngineBase::startBlocking(0x6d215ad8, 0x80000000, 0x50e20, 0x2cda0, 0x2cc00, 0x80000000), at 0xfe0fdb98
[2] QtConcurrent::ThreadEngineStarter<QList<QImage> >::startBlocking(0xffbfe9ec, 0xffbfe914, 0x511f8, 0xffbfea74, 0x6d617064, 0xffbfebf7), at 0x168ec
[3] QtConcurrent::blockingMappedReduced<QList<QImage>,QImage,const QImage&,void,QList<QImage>,const QImage&>(0xffbfe9ec, 0x0, 0x16644, 0xffbfe980, 0xffbfe97c, 0x157e8), at 0x168c8
[4] QtConcurrent::blockingMapped<QList<QImage>,QImage,QImage,const QImage&>(0xffbfe9ec, 0xffbfe9fc, 0x2, 0x0, 0x2c9e8, 0x16644), at 0x166ec
[5] main(0x1, 0xffbfe9f0, 0x15400, 0xffbfe9fc, 0x2cd70, 0x2cc00), at 0x15920