Appends the string to the buffer.
Only use them on normally allocated memory, or on buffers created from icalmemory_new_buffer, never with buffers created by icalmemory_tmp_buffer. If icalmemory_append_string has to resize a buffer on the ring, the ring will loose track of it an you will have memory problems.
| buf |
The buffer to be appended. It should not be the memory in ical. |
| pos |
The position at which the new string to be appended |
| str |
The string to be allocated |
| buf_size |
The size of the buffer before appended |