Add back option to scroll in stdin buffers

Commit 582c3c56b (Do not add trailing newline to non-scrolling fifo
buffers, 2024-01-28) completely forgot about stdin buffers,
breaking the ability to make them scrolling via "ge".
For example

	while sleep 1; do
	    seq $LINES
	    date
	done | kak

Let's fix that by adding the trailing newline back for stdin buffers.
Unlike "edit -scroll", don't scroll until the user explicitly moves
the cursor.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/buffer_utils.hh b/src/buffer_utils.hh
index e0b40425..bc0dab68 100644
--- a/src/buffer_utils.hh
+++ b/src/buffer_utils.hh
@@ -72,7 +72,8 @@ ColumnCount column_length(const Buffer& buffer, ColumnCount tabstop, LineCount l
 ByteCount get_byte_to_column(const Buffer& buffer, ColumnCount tabstop,
                              DisplayCoord coord);
 
-Buffer* create_fifo_buffer(String name, int fd, Buffer::Flags flags, bool scroll = false);
+enum class AutoScroll { No, NotInitially, Yes };
+Buffer* create_fifo_buffer(String name, int fd, Buffer::Flags flags, AutoScroll scroll);
 Buffer* create_buffer_from_string(String name, Buffer::Flags flags, StringView data);
 Buffer* open_file_buffer(StringView filename,
                          Buffer::Flags flags = Buffer::Flags::None);