There's little need for us to dynamically load it. The reasons why that
was necessary aren't in the public history (Qt 4.5 already had it[1]). I
remember writing the code in 2007-2008, I just don't remember why.
On modern Linux and FreeBSD, there's no libresolv.so any more and those
symbols have been rolled up into libc.so. It's still necessary on Darwin
systems, so this commit introduces WrapResolv.
It also resolves the unity build issues relating to libresolv symbols.
[1] https://code.qt.io/cgit/qt/qt.git/tree/src/network/kernel/qhostinfo_unix.cpp?h=v4.5.1
Task-number: QTBUG-109394
Change-Id: Ic5799e4d000b6c9395109e008780643bac52122b
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>