patch 8.2.3210: Vim9: searchpair() sixth argument is compiled

Problem:    Vim9: searchpair() sixth argument is compiled. (Yegappan
            Lakshmanan)
Solution:   Only compile the fifth argument.
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 5ec3b3d..2df5ff4 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -3315,7 +3315,7 @@
 	    return FAIL;
 	++*argcount;
 
-	if (is_searchpair && *argcount >= 5
+	if (is_searchpair && *argcount == 5
 		&& cctx->ctx_instr.ga_len == instr_count + 1)
 	{
 	    isn_T *isn = ((isn_T *)cctx->ctx_instr.ga_data) + instr_count;