MEDIUM: compression: don't send leading zeroes with chunk size

Till now we used to rely on a fixed maximum chunk size. Thanks to last
commit we're now free to adjust the chunk's length before sending the
data, so we don't have to use 6 digits all the time anymore, and if
one wants buffers larger than 16 MB it is now possible.
diff --git a/include/proto/compression.h b/include/proto/compression.h
index a2e80b8..5eeb5c7 100644
--- a/include/proto/compression.h
+++ b/include/proto/compression.h
@@ -30,7 +30,7 @@
 int comp_append_type(struct comp *comp, const char *type);
 int comp_append_algo(struct comp *comp, const char *algo);
 
-int http_emit_chunk_size(char *out, unsigned int chksz, int add_crlf);
+int http_emit_chunk_size(char *end, unsigned int chksz);
 int http_compression_buffer_init(struct session *s, struct buffer *in, struct buffer *out);
 int http_compression_buffer_add_data(struct session *s, struct buffer *in, struct buffer *out);
 int http_compression_buffer_end(struct session *s, struct buffer **in, struct buffer **out, int end);