bump libzpool soname

following commit ec311430e2fd66492498a1559f56ef25e1192266 ZFS
upstream due to

> Added functions (2):
> - boolean_t zpool_is_draid_spare(const char *);
> - zpool_compat_status_t zpool_load_compat(const char *,
>      boolean_t *, char *, char *);

However since libzfs increased both the current as well as the age,
as there where only addition but no changes of previously existing
ABI, the soname of the library remained at libzfs4.so - following
https://www.debian.org/doc/debian-policy/ch-sharedlibs.html I left
the package name at libzfs4linux

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
 [ Thomas: added a bit more context ]
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

Makefile

@@ -13,7 +13,7 @@ libpam-zfs_${ZFSPKGVER}_amd64.deb		\
 libuutil3linux_${ZFSPKGVER}_amd64.deb		\
 libzfs4linux_${ZFSPKGVER}_amd64.deb		\
 libzfsbootenv1linux_${ZFSPKGVER}_amd64.deb	\
-libzpool4linux_${ZFSPKGVER}_amd64.deb		\
+libzpool5linux_${ZFSPKGVER}_amd64.deb		\
 zfs-test_${ZFSPKGVER}_amd64.deb			\
 zfsutils-linux_${ZFSPKGVER}_amd64.deb		\
 zfs-zed_${ZFSPKGVER}_amd64.deb

debian/control

@@ -70,7 +70,7 @@ Depends: libssl-dev | libssl1.0-dev,
          libuutil3linux (= ${binary:Version}),
          libzfs4linux (= ${binary:Version}),
          libzfsbootenv1linux (= ${binary:Version}),
-         libzpool4linux (= ${binary:Version}),
+         libzpool5linux (= ${binary:Version}),
          ${misc:Depends}
 Provides: libnvpair-dev, libuutil-dev
 Description: OpenZFS filesystem development files for Linux
@@ -78,7 +78,7 @@ Description: OpenZFS filesystem development files for Linux
  libraries of OpenZFS filesystem.
  .
  This package includes the development files of libnvpair3, libuutil3,
- libzpool4 and libzfs4.
+ libzpool5 and libzfs4, libzfsbootenv1.
 
 Package: libzfs4linux
 Section: contrib/libs
@@ -106,7 +106,7 @@ Description: OpenZFS filesystem library for Linux
  .
  The zfsbootenv library provides support for modifying ZFS label information.
 
-Package: libzpool4linux
+Package: libzpool5linux
 Section: contrib/libs
 Architecture: linux-any
 Depends: ${misc:Depends}, ${shlibs:Depends}
@@ -274,7 +274,7 @@ Suggests: libnvpair3linux-dbgsym,
          libuutil3linux-dbgsym,
          libzfs4linux-dbgsym,
          libzfsbootenv1linux-dbgsym,
-         libzpool4linux-dbgsym,
+         libzpool5linux-dbgsym,
          zfs-test-dbgsym,
          zfsutils-linux-dbgsym,
          zfs-zed-dbgsym,