git add -i: handle CR/LF line endings in the interactive input

As of Git for Windows v2.27.0, there is an option to use Windows'
newly-introduced Pseudo Console support. When running an interactive add
operation with this support enabled, Git will receive CR/LF line
endings.

Therefore, let's not pretend that we are expecting Unix line endings.

This fixes #2729

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

prompt.c

@@ -78,7 +78,7 @@ int git_read_line_interactively(struct strbuf *line)
 	int ret;
 
 	fflush(stdout);
-	ret = strbuf_getline_lf(line, stdin);
+	ret = strbuf_getline(line, stdin);
 	if (ret != EOF)
 		strbuf_trim_trailing_newline(line);