QFileDialog won't compile on Solaris

QTBUG-3265 is included in 4.8 which causes compilation error on Solaris.

In qfiledialog.cpp: qt_tildeExpansion() calls system function "getpwnam_r()"

which has two definitions depending on the _POSIX_C_SOURCE version (see pwd.h):

int getpwnam_r(const char *, struct passwd *, char *, int, struct passwd **);
struct passwd *getpwnam_r(const char *, struct passwd *, char *, int);

Current version of "qt_tildeExpansion()" assumes that the first definition is always used.
But this is broken when the _POSIX_C_SOURCE is less than 199506L

Proposal is to slightly modify the code as follows:

...
int err = 0;
#if defined(Q_OS_SOLARIS) && defined(_POSIX_C_SOURCE - 0 >= 199506L)
tmpPw = getpwnam_r(userName.toLocal8Bit().constData(), &pw, buf, bufSize);
#else
err = getpwnam_r(userName.toLocal8Bit().constData(), &pw, buf, bufSize, &tmpPw);
#endif
...