package/sngrep: fix build with musl libc

Add upstream patch fixing typo that causes build failure under musl,
where stdin is constant.

Fixes:
http://autobuild.buildroot.net/results/ab827021d4dae8ae98f667328e4a9a7e1c4288d0/
http://autobuild.buildroot.net/results/e99e937c05be38d33e029fbfc737665b590c33bd/
http://autobuild.buildroot.net/results/e8ca0a40d8cd2c333b55fa9e67ddeead1f502d5a/

Cc: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/sngrep/0001-capture-fix-typo-in-FILE-object.patch

@@ -0,0 +1,43 @@
+From 604f6d0ce2ec42ac494d76c95e68850ea6e7da8f Mon Sep 17 00:00:00 2001
+From: Sebastian Kemper <sebastian_ml@gmx.net>
+Date: Sun, 4 Nov 2018 16:58:00 +0100
+Subject: [PATCH] capture: fix typo in FILE object
+
+FILE *fstdin is defined, but when calling freopen() stdin is used instead
+of fstdin.
+
+This causes the compile to fail:
+
+  CC       sngrep-capture.o
+capture.c: In function 'capture_offline':
+capture.c:194:21: error: assignment of read-only variable 'stdin'
+         if (!(stdin = freopen("/dev/tty", "r", stdin))) {
+                     ^
+make[5]: *** [Makefile:519: sngrep-capture.o] Error 1
+
+This commit fixes the typo.
+
+Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>
+Signed-off-by: Baruch Siach <baruch@tkos.co.il>
+---
+Upstream status: commit 604f6d0ce2ec
+
+ src/capture.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/capture.c b/src/capture.c
+index 911c35f43a35..a799413e2b0e 100644
+--- a/src/capture.c
++++ b/src/capture.c
+@@ -191,7 +191,7 @@ capture_offline(const char *infile, const char *outfile)
+ 
+     // Reopen tty for ncurses after pcap have used stdin
+     if (!strncmp(infile, "/dev/stdin", 10)) {
+-        if (!(stdin = freopen("/dev/tty", "r", stdin))) {
++        if (!(fstdin = freopen("/dev/tty", "r", stdin))) {
+             fprintf(stderr, "Failed to reopen tty while using stdin for capture.");
+             return 1;
+         }
+-- 
+2.19.2
+