CSV files saved by Calc on *nix systems save with line feeds all by their lonesome. From https://tools.ietf.org/html/rfc4180:
"Each record is located on a separate line, delimited by a line break (CRLF)."
Steps to Reproduce:
1. Enter some data in a new Calc document, or open any spreadsheet containing static data on a single sheet.
2. Save as CSV.
The resulting CSV file's line breaks consist of LF characters.
The resulting CSV file's line breaks consist of CRLF sequences.
User Profile Reset: No
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36
From the same source and same paragraph there,
"While there are various specifications and implementations for the
CSV format (for ex. , ,  and ), there is no formal
specification in existence, which allows for a wide variety of
interpretations of CSV files. "
But you are right, that there should be an additional option in the save as dialog to choose the record delimiter. Such wish is already tracked in bug 59041.
*** This bug has been marked as a duplicate of bug 59041 ***