removed c89 restriction

I had to remove the c89 restriction to make nn build.
Otherwise I get this error:
```
In file included from generic/THVector.c:1:0,
                from /home/mike/.local/include/torch/TH/THVector.h:566,
                from /home/mike/.local/include/torch/TH/TH.h:11,
                from /home/mike/devel/nn/init.c:1:
/home/mike/.local/include/torch/TH/generic/THVector.c:6:18: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
 static TH_INLINE void THVector_(fill)(real *x, const real c, const long n) {
```

The reason is torch was built without the c89 restriction, so `TH_INLINE` was defined to `inline` and used in `THVector.c`. In c89, the `inline` keyword doesn't seem to be recognized so it fails when nn is built.

Is this c89 flag mandatory for nn?