Do not allocate more memory than needed in the easy interfaces.
And compute m_boxed_len as (ZEROBYTES || message len) to match the way the
documentation describes the output.
Merge branch 'master' of github.com:jedisct1/libsodium

* 'master' of github.com:jedisct1/libsodium:
  Avoid naming a function select() in order to avoid confusion with select(2)
  Comment dead code generated by qhasm
  Remove useless access() before open()
  Add annotations for Coverity FPs
  test/default/sign.c: make the test vectors static
  Make crypto_sign() test code more explicit. crypto_sign() doesn't just need the secret key. The public key has to follow. Which is why the test vectors are laid out in this order. But this can confuse static analysis, as well as people looking at the test in order to better understand how crypto_sign() works. So, just copy the sk and the pk into a dedicated buffer, for clarity.
  Disable the pwhash_scrypt_ll test that requires 1 Gb RAM. This is way too much for many devices and for VPS users.
Add coverity scan