[PATCH 5/6] Remove dead code

[Steven Bosscher]

On Sat, Jun 14, 2014 at 9:48 PM, Richard Sandiford wrote:
> This patch removes some dead code that would otherwise need to be
> changed in the final patch.

These functions were intended to allow passes to update DF info
manually. That never was a very practical idea, apparently.

> gcc/
>         * df.h (df_ref_create, df_ref_remove): Delete.
>         * df-scan.c (df_ref_create, df_ref_compress_rec): Likewise.
>         (df_ref_remove): Likewise.

OK.

Ciao!
Steven