Perl: removed unneeded NGX_DONE test.

The NGX_DONE test in ngx_http_perl_handle_request() was introduced
in 1702:86bb52e28ce0, which also modified ngx_http_perl_call_handler()
to return NGX_DONE with c->destroyed.  The latter part was then
removed in 3050:f54b02dbb12b, so NGX_DONE test is no longer needed.
diff --git a/src/http/modules/perl/ngx_http_perl_module.c b/src/http/modules/perl/ngx_http_perl_module.c
index 6d3be91..d06b43c 100644
--- a/src/http/modules/perl/ngx_http_perl_module.c
+++ b/src/http/modules/perl/ngx_http_perl_module.c
@@ -228,11 +228,6 @@
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                    "perl handler done: %i", rc);
 
-    if (rc == NGX_DONE) {
-        ngx_http_finalize_request(r, rc);
-        return;
-    }
-
     if (rc > 600) {
         rc = NGX_OK;
     }