regen-makefile.sh: add link to related Debian bug in comment

This makes it easier to track when this workaround can be disabled once
Debian/upstream (hopefully) resolve the issue.

Change-Id: I3c4ed0ae5c1145f162b2745f4a46705b51874b5b
diff --git a/regen-makefile.sh b/regen-makefile.sh
index b8be4ea..a9f8562 100755
--- a/regen-makefile.sh
+++ b/regen-makefile.sh
@@ -6,6 +6,8 @@
 # the binaries to different paths without patching the make file
 # generator, leading in inconsistent non-working Makefiles.
 #
+# See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=884303 for details.
+#
 # The regexes below patch the generated Makefile to work on Debian 9 and
 # unstable, so far tested with TITAN 6.1.0, 6.2.0 and 6.3.0
 #