Bugfix - rewrite .d file path from abs to rel

[venkrao]

If the cache-hit is via preprocessor mode, then, the absolute paths in the .d files are not translated to relative. This is a bugfix for that problem.

[jrosdahl]

I replied to your mail on the ccache list before I saw this pull request.

What do you think about

--- a/ccache.c
+++ b/ccache.c
@@ -1964,11 +1964,6 @@ from_cache(enum fromcache_call_mode mode, bool put_object_in_manifest)
                update_mtime(cached_dwo);
        }
 
-       if (generating_dependencies && mode == FROMCACHE_CPP_MODE
-           && !conf->read_only && !conf->read_only_direct) {
-               put_file_in_cache(output_dep, cached_dep);
-       }
-
        send_cached_stderr();
 
        if (put_object_in_manifest) {

as a fix?

[jrosdahl]

I committed my suggestion in 04c6075.