Fix friend class statement

src/xlsx/xlsxstyles_p.h

@@ -61,7 +61,7 @@ public:
 
 private:
     friend class Format;
-    friend class StylesTest;
+    friend class ::StylesTest;
 
     void writeNumFmts(XmlStreamWriter &writer);
     void writeFonts(XmlStreamWriter &writer);

src/xlsx/xlsxworksheet.h

@@ -79,7 +79,7 @@ public:
 private:
     friend class Package;
     friend class Workbook;
-    friend class WorksheetTest;
+    friend class ::WorksheetTest;
     Worksheet(const QString &sheetName, Workbook *book);
 
     void saveToXmlFile(QIODevice *device);