Added fprintf error handling for freesasa_log().
Added fprintf error handling for freesasa_log().

JoaoRodrigues/freesasa,mittinatten/freesasa,JoaoRodrigues/freesasa,mittinatten/freesasa,JoaoRodrigues/freesasa,JoaoRodrigues/freesasa,mittinatten/freesasa,mittinatten/freesasa