Remove default argument from declarations of qHash as friend

It's illegal in C++11: §8.3.6.4 [dcl.fct.default]
"If a friend declaration specifies a default argument expression,
that declaration shall be a definition and shall be the only declaration
of the function or function template in the translation unit."

Clang is starting to enforce this, thus it's making qtbase not compiling.

Task-number: QTBUG-32100
Change-Id: Ifd9d4f62354d7cf4ccf275f36aab64e05c59efff
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Cocoa: Re-establish platform menu QObject hierarchy

This amends commit 119882714f87ffeb6945fdb2d02997ae125ff50c.

Change-Id: Ifb105596af5b00b04344cb665b3e68292c9187ae
Reviewed-by: Romain Perier <romain.perier@gmail.com>
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>