Silence clang warnings

enclink.c:127:6: warning: cast from 'char *' to 'uint32_t *' (aka 'unsigned int *') increases required alignment from 1 to 4 [-Wcast-align]
    *(uint32_t *) & key[0] = prand(&seed, 0xFFFFFFFF);
     ^~~~~~~~~~~~~~~~~~~~~
enclink.c:128:6: warning: cast from 'char *' to 'uint32_t *' (aka 'unsigned int *') increases required alignment from 1 to 4 [-Wcast-align]
    *(uint32_t *) & key[4] = prand(&seed, 0xFFFFFFFF);
     ^~~~~~~~~~~~~~~~~~~~~
enclink.c:129:6: warning: cast from 'char *' to 'uint32_t *' (aka 'unsigned int *') increases required alignment from 1 to 4 [-Wcast-align]
    *(uint32_t *) & key[8] = prand(&seed, 0xFFFFFFFF);
     ^~~~~~~~~~~~~~~~~~~~~
enclink.c:130:6: warning: cast from 'char *' to 'uint32_t *' (aka 'unsigned int *') increases required alignment from 1 to 4 [-Wcast-align]
    *(uint32_t *) & key[12] = prand(&seed, 0xFFFFFFFF);
     ^~~~~~~~~~~~~~~~~~~~~~
4 warnings generated.
Silence clang warnings by removing unused len param

net.c:1191:29: warning: cast from 'int *' to 'size_t *' (aka 'unsigned long *') increases required alignment from 4 to 8 [-Wcast-align]
            link_read(i, s, (size_t *) len);
                            ^~~~~~~~~~~~~~
net.c:1298:23: warning: cast from 'int *' to 'size_t *' (aka 'unsigned long *') increases required alignment from 4 to 8 [-Wcast-align]
    link_read(ret, s, (size_t *) len);
                      ^~~~~~~~~~~~~~
Silence clang warning

shell.c:242:11: warning: cast from 'char *' to 'struct ifreq *' increases required alignment from 1 to 8 [-Wcast-align]
    ifr = (struct ifreq *) reqp;        /* start examining interface */
          ^~~~~~~~~~~~~~~~~~~~~
Merge branch 'clang-warnings' into next

* clang-warnings:
  Silence clang warning
  Silence clang warnings by removing unused len param
  Silence clang warnings