[4.9-debian] Fix build under Debian9

Previously I was building this package from under Debian10 and it was
working ok. But trying to build in pristine Debian9 environment revealed
that there is not debhelper-compat support at that version. Adjust
control correspondingly (see debian/changelog for details). I've verified
that the resulting built deb is exactly the same as it was before this
change when built on Debian10.

fs/fuse/debian/changelog

+nxd-fuse (4.9.nxd3+debian2) stretch; urgency=medium
+
+  * Switch `Build-Depends: debhelper-compat (= 12)` to `debian/compat = 10`:
+    - on Debian9 there is no support for `Build-Depends: debhelper-compat`.
+    - on Debian9 the latest supported compatibility level is 10.
+
+ -- Kirill Smelkov <kirr@nexedi.com>  Sun, 11 Oct 2020 10:54:14 +0300
+
 nxd-fuse (4.9.nxd3+debian1) stretch; urgency=medium
 
   * No change; corresponds to nxd-fuse 4.19.nxd3+debian1 regarding patches and

fs/fuse/debian/compat

+10

fs/fuse/debian/control

@@ -3,7 +3,7 @@ Section: kernel
 Priority: optional
 Maintainer: Kirill Smelkov <kirr@nexedi.com>
 Build-Depends:
- debhelper-compat (= 12),
+ debhelper,
  dkms,
 Rules-Requires-Root: no
 Standards-Version: 4.3.0