use #pragma comment(lib) with _MSC_VER only

use #pragma comment(lib) with _MSC_VER only

Avoid this warning when compiled with llvm/gcc + mingw-w64 and
`USE_BCRYPTGENRANDOM` enabled:

```
../providers/implementations/rands/seeding/rand_win.c:31:11: warning: unknown pragma ignored [-Wunknown-pragmas]
          ^
1 warning generated.
```

CLA: trivial

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18709)