patch 8.1.1971: manually enabling features causes build errors

Problem:    Manually enabling features causes build errors. (John Marriott)
Solution:   Adjust #ifdefs.
diff --git a/src/proto.h b/src/proto.h
index 05a7cf8..cc31726 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -181,9 +181,7 @@
 # if defined(FEAT_PROFILE) || defined(FEAT_RELTIME)
 # include "profiler.pro"
 # endif
-# ifdef FEAT_QUICKFIX
-#  include "quickfix.pro"
-# endif
+# include "quickfix.pro"
 # include "regexp.pro"
 # include "scriptfile.pro"
 # include "screen.pro"