patch 8.2.0690: line number of option set by modeline is wrong

Problem:    Line number of option set by modeline is wrong.
Solution:   Do not double the line number. (Ozaki Kiichi, closes #6035)
diff --git a/src/option.c b/src/option.c
index 3f97c3c..8574f7f 100644
--- a/src/option.c
+++ b/src/option.c
@@ -2460,7 +2460,9 @@
     int		indir = (int)options[opt_idx].indir;
     sctx_T	new_script_ctx = script_ctx;
 
-    new_script_ctx.sc_lnum += SOURCING_LNUM;
+    // Modeline already has the line number set.
+    if (!(opt_flags & OPT_MODELINE))
+	new_script_ctx.sc_lnum += SOURCING_LNUM;
 
     // Remember where the option was set.  For local options need to do that
     // in the buffer or window structure.