Use count()

Co-authored-by: Daniel Marjamäki <daniel.marjamaki@gmail.com>

Author: chrchr-github

lib/checkunusedvar.cpp

@@ -1423,7 +1423,7 @@ void CheckUnusedVar::checkFunctionVariableUsage()
                      !(var->valueType() && var->valueType()->container) &&
                      !(var->isStatic() && isReturnedByRef(var, scope->function)))
                 unassignedVariableError(usage._var->nameToken(), varname);
-            else if (!usage._var->isMaybeUnused() && !usage._modified && !usage._read && var && diagUnreadVariable.find(usage._var) == diagUnreadVariable.end()) {
+            else if (!usage._var->isMaybeUnused() && !usage._modified && !usage._read && var && diagUnreadVariable.count(usage._var) == 0) {
                 const Token* vnt = var->nameToken();
                 bool error = false;
                 if (vnt->next()->isSplittedVarDeclEq() || (!var->isReference() && vnt->strAt(1) == "=")) {