Improve QColor <==> #AARRGGBB conversion

tests/auto/styles/tst_stylestest.cpp

@@ -81,7 +81,7 @@ void StylesTest::testSolidFillBackgroundColor()
 
     QByteArray xmlData = styles.saveToXmlData();
 
-    QVERIFY(xmlData.contains("<patternFill patternType=\"solid\"><fgColor rgb=\"FFff0000\"/>"));
+    QVERIFY(xmlData.contains("<patternFill patternType=\"solid\"><fgColor rgb=\"FFFF0000\"/>"));
 }
 
 void StylesTest::testWriteBorders()

tests/auto/xlsxconditionalformatting/tst_conditionalformattingtest.cpp

@@ -93,7 +93,7 @@ void ConditionalFormattingTest::testDataBarRules()
     QByteArray res = "<cfRule type=\"dataBar\" priority=\"1\">"
             "<dataBar><cfvo type=\"min\" val=\"0\"/>"
             "<cfvo type=\"max\" val=\"0\"/>"
-            "<color rgb=\"FF0000ff\"/></dataBar>"
+            "<color rgb=\"FF0000FF\"/></dataBar>"
             "</cfRule>";
     QVERIFY(buffer.buffer().contains(res));
 }