always specify mtu for ipv6 address
Merge pull request #106 from kytvi2p/fix_makefiles

Makefile updates
split SSU to SSU and SSUSession
split SSU to SSU and SSUSession
0.2.0
allow LDFLAGS to be set by user

Move old LDFLAGS variable to LDLIBS. By doing ths, a user can set their
own LDFLAGS without breaking the build. A case in which this can be
useful is hardening with debian, e.g.

    $ dpkg-buildflags --get LDFLAGS
    -Wl,-z,relro
allow AESNI to be disabled