QSharedMemory: fix -Werror=deprecated in C++20 build

Capture of *this by reference in [=] is deprecated in C++20. Use the
perfectly adequate [&] instead.

Amends 0740ab5.

Change-Id: I3035a29baf63c22a32aafdcbd4425a3f7b45472f
Reviewed-by: Giuseppe D'Angelo <[email protected]>
Reviewed-by: Thiago Macieira <[email protected]>

src/corelib/ipc/qsharedmemory_p.h

@@ -170,23 +170,23 @@ class Q_AUTOTEST_EXPORT QSharedMemoryPrivate : public QObjectPrivate
 
     bool handle()
     {
-        return visit([=](auto p) { return !!p->handle(this); });
+        return visit([&](auto p) { return !!p->handle(this); });
     }
     bool cleanHandle()
     {
-        return visit([=](auto p) { return p->cleanHandle(this); });
+        return visit([&](auto p) { return p->cleanHandle(this); });
     }
     bool create(qsizetype size)
     {
-        return visit([=](auto p) { return p->create(this, size); });
+        return visit([&](auto p) { return p->create(this, size); });
     }
     bool attach(QSharedMemory::AccessMode mode)
     {
-        return visit([=](auto p) { return p->attach(this, mode); });
+        return visit([&](auto p) { return p->attach(this, mode); });
     }
     bool detach()
     {
-        return visit([=](auto p) { return p->detach(this); });
+        return visit([&](auto p) { return p->detach(this); });
     }
 
     inline void setError(QSharedMemory::SharedMemoryError e, const QString &message)