libksba: drop -unknown suffix from version number

libksba: drop -unknown suffix from version number

Include drop-unknown-suffix.inc to remove unknown suffix from version in
pc file.

Befor the fix:
$ cat /usr/lib/pkgconfig/ksba.pc
[snip]
Name: ksba
Description: X.509 and CMS support library
Requires: gpg-error
Version: 1.6.7-unknown
Cflags: -I${includedir}
[snip]

After the fix:
$ cat /usr/lib/pkgconfig/ksba.pc
[snip]
Name: ksba
Description: X.509 and CMS support library
Requires: gpg-error
Version: 1.6.7
Cflags: -I${includedir}
[snip]

Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>