BUG/MINOR: chunk: Fix tests on the chunk size in functions copying data

When raw data are copied or appended in a chunk, the result must not exceed the
chunk size but it can reach it. Unlike functions to copy or append a string,
there is no terminating null byte.

This patch must be backported as far as 1.8. Note in 1.8, the functions
chunk_cpy() and chunk_cat() don't exist.

(cherry picked from commit 48fa033f2809af265c230a7c7cf86413b7f9909b)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/include/common/chunk.h b/include/common/chunk.h
index a1a3eb7..18abca7 100644
--- a/include/common/chunk.h
+++ b/include/common/chunk.h
@@ -98,7 +98,7 @@
 /* copies chunk <src> into <chk>. Returns 0 in case of failure. */
 static inline int chunk_cpy(struct buffer *chk, const struct buffer *src)
 {
-	if (unlikely(src->data >= chk->size))
+	if (unlikely(src->data > chk->size))
 		return 0;
 
 	chk->data  = src->data;
@@ -109,7 +109,7 @@
 /* appends chunk <src> after <chk>. Returns 0 in case of failure. */
 static inline int chunk_cat(struct buffer *chk, const struct buffer *src)
 {
-	if (unlikely(chk->data + src->data >= chk->size))
+	if (unlikely(chk->data + src->data > chk->size))
 		return 0;
 
 	memcpy(chk->area + chk->data, src->area, src->data);
@@ -123,7 +123,7 @@
 static inline int chunk_memcpy(struct buffer *chk, const char *src,
 			       size_t len)
 {
-	if (unlikely(len >= chk->size))
+	if (unlikely(len > chk->size))
 		return 0;
 
 	chk->data  = len;
@@ -138,7 +138,7 @@
 static inline int chunk_memcat(struct buffer *chk, const char *src,
 			       size_t len)
 {
-	if (unlikely(chk->data + len >= chk->size))
+	if (unlikely(chk->data + len > chk->size))
 		return 0;
 
 	memcpy(chk->area + chk->data, src, len);