Replace the qCpuHasFeature function with a macro

We want to make sure that there's a constant propagation from the static
variable that is filled in with the current code-generation options.
With most compilers in debug mode, we'd carry dead code. With MSVC, even
inlining is really bad even in release mode, and it doesn't perform
constant propagation even with __forceinline.

Change-Id: I7a95ff6622b864771243990bb5e205b2df0c33fc
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Fix bad CSS color: O (the letter) is not a valid hex digit

Found by: Tomaz Canabrava <tcanabrava@kde.org>
Change-Id: Ia1b5b00819cf4b145d1384aacbd54ed9a23aa6a3
Reviewed-by: Dirk Hohndel
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
QSpinBox: allow positive values to be entered with the '+' prefix.

The code was there to do it, but it was using minimumValue instead of
maximumValue to test if the '+' should be allowed.

Task-number: QTBUG-20691

[ChangeLog][QtWidgets][QSpinBox] Entering positive values with the '+'
prefix is now allowed.

Change-Id: Iff62d073e350dc9a33b7e06e4b492048c74437c4
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>