Author: Reiner Herrmann <reiner@reiner-h.de>
Description: Fix FTBFS with GCC 10
 curwin is declared in different source file. declare it as extern
 to fix multiple definition linker error.
Bug-Debian: https://bugs.debian.org/966191

--- a/src/locfit/startlf.c
+++ b/src/locfit/startlf.c
@@ -233,7 +233,7 @@
 extern lfit lf;
 extern design des;
 extern plots pl[];
-int curwin;
+extern int curwin;
 vari *vb;
 
 INT nofit()