BUG #13061. Renaming QT_WIDGETS_DISABLE_QTWEBKIT

Renaming QT_WIDGETS_DISABLE_QTWEBKIT to PQWIDGETS_DISABLE_QTWEBKIT to match the
name of the module.

Change-Id: Id2934e0d6bd58682c56e72553bd4e4e9794dc4cc
Merge topic '13061_make_webkit_optional' into next

e0cc7fe BUG #13061. Renaming QT_WIDGETS_DISABLE_QTWEBKIT
Fixed typo in fix for BUG #13061.

Change-Id: If4c5d7ff2dedf3bac6bc41817d2243b0f99165d3
Merge topic '13061_make_webkit_optional' into next

d60727f Fixed typo in fix for BUG #13061.