Clean up tst_QProgressDialog

Remove empty ctor and dtor.

Change-Id: Ib89f463eb2623bbb66cc3faa2ab2d5992810f153
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: David Faure <david.faure@kdab.com>
tst_QProgressDialog: enable topLevelWindows() check in cleanup()

Detects widget leaks.

Change-Id: Ia2287debc96a5b87b224b887661679eba8622dc0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: David Faure <david.faure@kdab.com>
QProgressDialog: don't crash when setting the same {bar,button,label} again

The associated test has unearthed that setBar() fails to make the new bar a child
of the progress dialog. This will be fixed in a separate commit.

Task-number: QTBUG-40502
Change-Id: I2d09ebb07ae6395449a4efe38a638df831eebdd7
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: David Faure <david.faure@kdab.com>
QProgressDialog: Extract Method QProgressDialogPrivate::setCancelButtonText()

This is in preparation of a fix for the broken online-retranslatability of
the cancel button.

Change-Id: Ie62540766e50e1f1ec07d251cc56a2ee0745d434
Reviewed-by: David Faure <david.faure@kdab.com>
QProgressDialog: make the cancel button retranslate on LanguageChange

It is documented to be, and the LanguageChange event is caught and processed.
However, retranslateStrings() uses QProgressDialog::setCancelButtonText(),
which unconditionally sets useDefaultCancelText=true, blocking any further
changes to the button text by subsequent LanguageChange events.

The fix is to use extracted QProgressDialogPrivate::setCancelButtonText()
which - quite intentionally - doesn't set useDefaultCancelText.

Task-number: QTBUG-40504
Change-Id: I6e701deda10c454cb088c0b0778ac2d6adff574a
Reviewed-by: David Faure <david.faure@kdab.com>
Use an enum to check that the OS is saving the register state

It's easier to read AVXState and AVX512State than 6 and 0xe6.

Also add a note that where we should have checked whether the SSE state
is being saved by the OS. However, we won't do it because it's just a
waste of CPU cycles: any OS Qt 5 runs on will enable the proper
state-saving.

Change-Id: Id87b59fe1388a6cab983c9412341e36a86dd15c5
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Add the detection of the compiler macros for more AVX512 features

Change-Id: I1d1f2c3857824b17185bc47398299ea7f92c5568
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>