BUG/MINOR: proxy: Missing calloc return value check in proxy_parse_declare

A memory allocation failure happening during proxy_parse_declare while
processing the "capture" keyword and allocating a cap_hdr structure
would have resulted in a crash. This function is only called during
configuration parsing.

It was raised in GitHub issue #1233.
It could be backported to all stable branches.

(cherry picked from commit 55ba0d6865662036d1d137dc4aac3841d29ad6d3)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 581d892c823ec18ff7066af696c2017c664959da)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 978b2d4a3dbc0a71786c78978c5eeb4c0c8e1b19)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 5d0653d26244c36eb07824697eab712a9781edd5)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/src/proxy.c b/src/proxy.c
index d0fc168..43490db 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -490,6 +490,10 @@
 
 		/* register the capture. */
 		hdr = calloc(1, sizeof(*hdr));
+		if (!hdr) {
+			memprintf(err, "proxy '%s': out of memory while registering a capture", curpx->id);
+			return -1;
+		}
 		hdr->name = NULL; /* not a header capture */
 		hdr->namelen = 0;
 		hdr->len = len;