patch 8.2.1680: Vim9: line number for compare error is wrong

Problem:    Vim9: line number for compare error is wrong.
Solution:   Set SOURCING_LNUM. (closes #6936)

Author: brammool

src/testdir/test_vim9_expr.vim

@@ -481,6 +481,7 @@ def Test_expr4_equal()
   set noignorecase
 
   CheckDefFailure(["let x = 'a' == xxx"], 'E1001:', 1)
+  CheckDefExecFailure(['let items: any', 'eval 1', 'eval 2', 'if items == []', 'endif'], 'E691:', 4)
 
   let bb = 0z3f
   assert_equal(true, 0z3f == bb)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1680,
 /**/
     1679,
 /**/

src/vim9execute.c

@@ -2126,6 +2126,7 @@ call_def_function(
 		    exptype_T	exptype = iptr->isn_arg.op.op_type;
 		    int		ic = iptr->isn_arg.op.op_ic;
 
+		    SOURCING_LNUM = iptr->isn_lnum;
 		    typval_compare(tv1, tv2, exptype, ic);
 		    clear_tv(tv2);
 		    --ectx.ec_stack.ga_len;