MINOR: stream: report the list of active filters on stream crashes

Now we very rarely catch spinning streams, and whenever we catch one it
seems a filter is involved, but we currently report no info about them.
Let's print the list of enabled filters on the stream with such a crash
to help with the reports. A typical output will now look like this:

  [ALERT] 121/165908 (1110) : A bogus STREAM [0x7fcaf4016a60] is spinning at 2 calls per second and refuses to die, aborting now! Please report this error to developers [strm=0x7fcaf4016a60 src=127.0.0.1 fe=l1 be=l1 dst=<CACHE> rqf=6dc42000 rqa=48000 rpf=a0040223 rpa=24000000 sif=EST,10008 sib=DIS,80110 af=(nil),0 csf=0x7fcaf4023c00,10c000 ab=0x7fcaf40235f0,4 csb=(nil),0 cof=0x7fcaf4016610,1300:H1(0x7fcaf4016840)/RAW((nil))/tcpv4(29) cob=(nil),0:NONE((nil))/NONE((nil))/NONE(0) filters={0x7fcaf4016fb0="cache store filter", 0x7fcaf4017080="compression filter"}]

This may be backported to 2.0.

(cherry picked from commit 9753d61288936db804628c1e0bad20b7593ad384)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 050bc434267032c60bc93531f9c508a49a2a50e1)
Signed-off-by: Willy Tarreau <w@1wt.eu>
diff --git a/src/stream.c b/src/stream.c
index 68972e3..a753dbb 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -2995,6 +2995,19 @@
 
 	chunk_reset(&trash);
 	stream_dump(&trash, s, "", ' ');
+
+	chunk_appendf(&trash, "filters={");
+	if (HAS_FILTERS(s)) {
+		struct filter *filter;
+
+		list_for_each_entry(filter, &s->strm_flt.filters, list) {
+			if (filter->list.p != &s->strm_flt.filters)
+				chunk_appendf(&trash, ", ");
+			chunk_appendf(&trash, "%p=\"%s\"", filter, FLT_ID(filter));
+		}
+	}
+	chunk_appendf(&trash, "}");
+
 	memprintf(&msg,
 	          "A bogus %s [%p] is spinning at %d calls per second and refuses to die, "
 	          "aborting now! Please report this error to developers "