Fix variable shadowing in qt/qvaluecombobox.cpp
Fix variable shadowing in qt/qvaluecombobox.cpp

qt/qvaluecombobox.cpp:15:34: warning: declaration shadows a field of 'QValueComboBox' [-Wshadow]
void QValueComboBox::setRole(int role) { this->role = role; }
                                 ^
./qt/qvaluecombobox.h:32:9: note: previous declaration is here
    int role;
        ^

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