convert: The native line-ending is \r\n on MinGW

convert: The native line-ending is \r\n on MinGW

If you try this:

 1. Install Git for Windows (from the msysgit project)

 2. Put

	[core]
		autocrlf = false
		eol = native

    in your .gitconfig.

 3. Clone a project with

	*.txt text

    in its .gitattributes.

Then with current git, any text files checked out have LF line
endings, instead of the expected CRLF.

Cc: Johannes Schindelin <redacted>
Cc: Johannes Sixt <redacted>
Signed-off-by: Jonathan Nieder <redacted>
Signed-off-by: Junio C Hamano <redacted>