base_cpp: added override for std::exception::what in embb::base::Exception

base_cpp/include/embb/base/exceptions.h

@@ -175,6 +175,16 @@ class Exception : public std::exception {
   }
 
   /**
+   * Returns the error message.
+   * This is here for compatibility with std::exception.
+   *
+   * \return Pointer to error message
+   */
+  virtual const char* what() const throw() {
+    return What();
+  }
+
+  /**
    * Returns an integer code representing the exception.
    *
    * \return %Exception code