Fix missing function declaration, so package could build with modern compilers
https://bugs.gentoo.org/886457
--- a/src/aprx/estim.c
+++ b/src/aprx/estim.c
@@ -41,6 +41,8 @@
     Bvec *u, Bvec *ud, Bvec *r);
 VEXTERNC void Aprx_estFaceBump(Aprx *thee, int color,
     Bvec *u, Bvec *ud, Bvec *r);
+VPUBLIC int Aprx_markRefineDorfler (Aprx *thee, double percentToRefine,
+    int color);
 
 /*
  * ***************************************************************************