Set the buffer's `comint-input-ring' from a history file.
The name of the file is given by the variable `comint-input-ring-file-name'.
The history ring is of size `comint-input-ring-size', regardless of file size.
If `comint-input-ring-file-name' is nil this function does nothing.
If the optional argument SILENT is non-nil, we say nothing about a
failure to read the history file.
This function is useful for major mode commands and mode hooks.
The commands stored in the history file are separated by the
`comint-input-ring-separator', and entries that match
`comint-input-history-ignore' are ignored. The most recent command
comes last.
See also `comint-input-ignoredups' and `comint-write-input-ring'.
(fn &optional SILENT)