Profile's LD_LIBRARY_PATH by default

[Sébastien Lerique]

Dear all,

This question could stem from a simpler example, but I think in 
this case it doesn't change much. So I'll go with my use case:

While running a racket program which uses OpenCV, I realised that 
my LD_LIBRARY_PATH does not contain my user's profile libs. I have 
`libopencv*.so` in `~/.guix-profile/lib/`, but running a racket 
program which needs that fails:

```
$ racket capture.rkt
ffi-lib: couldn't open "libopencv_core.so" (libopencv_core.so: 
cannot open shared object file: No such file or directory)
```

While running

```
env LD_LIBRARY_PATH=/home/sl/.guix-profile/lib/ racket capture.rkt
```

works.

(Also, this <http://0x0.st/ik3s.txt> is the output of `env 
LD_DEBUG=libs racket capture.rkt`.)

Is this normal behaviour, i.e. that the path to dynamic libs 
installed in my user profile should be manually configured in my 
shell startup scripts? Should this not be included in 
`~/.guix-profile/etc/profile`?

Thanks all, and best wishes!
Sébastien