diff: simplify color_moved check when flushing

diff: simplify color_moved check when flushing

In diff_flush_patch_all_file_pairs(), we set o->emitted_symbols if and
only if o->color_moved is true. That causes the lower-level routines to
fill up o->emitted_symbols, which we then analyze in order to do the
actual colorizing.

But in that final step, we do:

  if (o->emitted_symbols) {
          if (o->color_moved) {
	     ...actual coloring...
	  }
	  ...clean up of emitted_symbols...
  }

The inner "if" will always trigger, since we set emitted_symbols only
when doing color_moved (it is a little confusing that it is set inside
the diff_options struct, but that is for convenience of passing it to
the lower-level routines; we always clear it at the end of flushing,
since 48edf3a02a (diff: clear emitted_symbols flag after use,
2019-01-24)).

Let's simplify the code a bit by just dropping the inner "if" and
running its block unconditionally.

In theory the current code might be useful if another feature besides
color_moved setup and used emitted_symbols, but it would be easy to
refactor later to handle that. And in the meantime, this makes further
work in this area easier.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>