patch 9.1.1314: max allowed string width too small

Problem:  max allowed string width too small
Solution: increased MAX_ALLOWED_STRING_WIDTH from 6400 to 1MiB
          (Hirohito Higashi)

closes: #17138

Co-authored-by: John Marriott <basilisk@internode.on.net>
Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/strings.c b/src/strings.c
index e1d23e3..84bec92 100644
--- a/src/strings.c
+++ b/src/strings.c
@@ -2782,7 +2782,7 @@
 	semsg(_(e_out_of_memory_allocating_nr_bytes), arglen);
 }
 
-#define MAX_ALLOWED_STRING_WIDTH 6400
+#define MAX_ALLOWED_STRING_WIDTH 1048576    // 1 MiB
 
     static int
 get_unsigned_int(