automake: Remove -ltomcrypt flag for stoken, stoken-gui

In theory, libstoken should pull in its own depedencies...

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
pkgconfig: Move libtomcrypt dependency to Requires.private

For the shared case: libstoken.so should always have a DT_NEEDED entry for
libtomcrypt.

For the static case: libstoken.a does need libtomcrypt to be explicitly
linked.

So, libtomcrypt should be listed under Requires.private, not Requires.

More info at: http://people.freedesktop.org/~dbn/pkg-config-guide.html

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>