Do not ignore cflags of c-file (#161)
Do not ignore cflags of c-file (#161)

For example:

```lisp
(defsystem "foo"
  :components ((:c-file "foo" :cflags ("-lz" "-lm"))))
```

The slot is already there, but isn't actually used. It's useful when
custom compilation options need to be passed.

Additionally, the cflags slot is removed from o-file, as it does not
make sense there. Nor is it used, anyway.
stassats/cffi,stassats/cffi,cffi/cffi,stassats/cffi,cffi/cffi,cffi/cffi