Partial fix for #12254 (cppcheck.cfg can't be loaded from relative paths anymore) (#5760)

Author: danmar

cli/cmdlineparser.cpp

@@ -1629,10 +1629,10 @@ void CmdLineParser::printHelp() const
     mLogger.printRaw(oss.str());
 }
 
-bool CmdLineParser::isCppcheckPremium() {
-    Settings settings;
-    settings.loadCppcheckCfg(); // TODO: how to handle errors?
-    return startsWith(settings.cppcheckCfgProductName, "Cppcheck Premium");
+bool CmdLineParser::isCppcheckPremium() const {
+    if (mSettings.cppcheckCfgProductName.empty())
+        mSettings.loadCppcheckCfg();
+    return startsWith(mSettings.cppcheckCfgProductName, "Cppcheck Premium");
 }
 
 bool CmdLineParser::tryLoadLibrary(Library& destination, const std::string& basepath, const char* filename)

cli/cmdlineparser.h

@@ -111,7 +111,7 @@ class CmdLineParser {
     void printHelp() const;
 
 private:
-    static bool isCppcheckPremium();
+    bool isCppcheckPremium() const;
 
     template<typename T>
     bool parseNumberArg(const char* const arg, std::size_t offset, T& num, bool mustBePositive = false)