REORG: channel: move buffer_{replace,insert_line}* to buffer.{c,h}
These functions do not depend on the channel flags anymore thus they're
much better suited to be used on plain buffers. Move them from channel
to buffer.
diff --git a/src/frontend.c b/src/frontend.c
index aa6cb9e..ffd1017 100644
--- a/src/frontend.c
+++ b/src/frontend.c
@@ -389,7 +389,7 @@
/* remove the PROXY line from the request */
len = line - req->buf.data;
- buffer_replace2(req, req->buf.data, line, NULL, 0);
+ buffer_replace2(&req->buf, req->buf.data, line, NULL, 0);
req->total -= len; /* don't count the header line */
req->analysers &= ~an_bit;