patch 8.2.5149: cannot build without the +eval feature

Problem:    Cannot build without the +eval feature. (Tony Mechelynck)
Solution:   Add #ifdefs.
diff --git a/src/ex_getln.c b/src/ex_getln.c
index b499aba..8dc03dc 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -1206,7 +1206,9 @@
 {
     int		i;
     int		c;
+#ifdef FEAT_EVAL
     int		save_new_cmdpos = new_cmdpos;
+#endif
 
 #ifdef USE_ON_FLY_SCROLL
     dont_scroll = TRUE;	// disallow scrolling here
@@ -1265,7 +1267,9 @@
 	}
 #endif
     }
+#ifdef FEAT_EVAL
     new_cmdpos = save_new_cmdpos;
+#endif
 
     // remove the double quote
     redrawcmd();