MINOR: buffer: replace buffer_empty() with b_empty() or c_empty()
For the same consistency reasons, let's use b_empty() at the few places
where an empty buffer is expected, or c_empty() if it's done on a channel.
Some of these places were there to realign the buffer so
{b,c}_realign_if_empty() was used instead.
diff --git a/src/channel.c b/src/channel.c
index c5a51f7..1efab9c 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -205,7 +205,7 @@
if (unlikely(channel_input_closed(chn)))
return NULL;
- if (!chn->buf->size || !buffer_empty(chn->buf))
+ if (!c_size(chn) || !c_empty(chn))
return buf;
old = chn->buf;