patch 8.2.3418: garbage collection while evaluating may cause trouble

Problem:    Garbage collection while evaluating may cause trouble.
Solution:   Disable garbage collection while evaluating an expression.
            (Christian Brabandt, issue #8848)

Author: chrisbra

src/eval.c

@@ -561,16 +561,19 @@ eval_to_string_safe(
     char_u	*retval;
     funccal_entry_T funccal_entry;
     int		save_sc_version = current_sctx.sc_version;
+    int		save_garbage = may_garbage_collect;
 
     current_sctx.sc_version = 1;
     save_funccal(&funccal_entry);
     if (use_sandbox)
 	++sandbox;
     ++textwinlock;
+    may_garbage_collect = FALSE;
     retval = eval_to_string(arg, FALSE);
     if (use_sandbox)
 	--sandbox;
     --textwinlock;
+    may_garbage_collect = save_garbage;
     restore_funccal();
     current_sctx.sc_version = save_sc_version;
     return retval;

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3418,
 /**/
     3417,
 /**/