Make libmariadb-dev depend on libssl-dev (Closes: #917135)

Anything that builds against libmariadb-dev expects to have libssl-dev
also available because libmariadb3 has these compilation flags:

pkg-config --libs libmariadb
-L/usr/lib/x86_64-linux-gnu/ -lmariadb -lz -ldl -lm -lpthread -lssl -lcrypto

debian/control

@@ -41,6 +41,7 @@ Architecture: any
 Multi-Arch: same
 Section: libdevel
 Depends: libmariadb3 (= ${binary:Version}),
+         libssl-dev | libssl1.0-dev,
          zlib1g-dev,
          ${misc:Depends},
          ${shlibs:Depends}