[master] 8bbbdfa Try to work around systems having unsigned char types.

[Poul-Henning Kamp]

commit 8bbbdfa3f4661aa5149a5ebc4e80167b4465312e
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Thu Jun 29 08:37:09 2017 +0000

    Try to work around systems having unsigned char types.

diff --git a/lib/libvarnishapi/vjsn.c b/lib/libvarnishapi/vjsn.c
index 01f10c2..6ae82fa 100644
--- a/lib/libvarnishapi/vjsn.c
+++ b/lib/libvarnishapi/vjsn.c
@@ -214,7 +214,7 @@ vjsn_string(struct vjsn *js)
 			js->err = "Unterminate string";
 			return (NULL);
 		}
-		if (*js->ptr >= 0x00 && *js->ptr <= 0x1f) {
+		if ((unsigned char)(*js->ptr) <= 0x1f) {
 			js->err = "unescaped control char in string";
 			return (NULL);
 		}