From https://github.com/plougher/squashfs-tools/pull/9

From 4280e74de14070869787a9166242f9ce2dafd82e Mon Sep 17 00:00:00 2001
From: Alexandru Ardelean <aa@ocedo.com>
Date: Wed, 6 Jan 2016 15:33:43 +0200
Subject: [PATCH] squashfs-tools: with fnmatch.h compatibility with musl

musl does not define FNM_EXTMATCH

Signed-off-by: Alexandru Ardelean <aa@ocedo.com>
---
 squashfs-tools/action.c         |  2 +-
 squashfs-tools/fnmatch_compat.h | 32 ++++++++++++++++++++++++++++++++
 squashfs-tools/mksquashfs.c     |  2 +-
 squashfs-tools/unsquashfs.c     |  1 +
 squashfs-tools/unsquashfs.h     |  1 -
 5 files changed, 35 insertions(+), 3 deletions(-)
 create mode 100644 squashfs-tools/fnmatch_compat.h

diff --git a/squashfs-tools/action.c b/squashfs-tools/action.c
index 35889a4..4b06ccb 100644
--- a/squashfs-tools/action.c
+++ b/squashfs-tools/action.c
@@ -31,7 +31,6 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
-#include <fnmatch.h>
 #include <pwd.h>
 #include <grp.h>
 #include <sys/wait.h>
@@ -43,6 +42,7 @@
 #include "mksquashfs.h"
 #include "action.h"
 #include "error.h"
+#include "fnmatch_compat.h"
 
 /*
  * code to parse actions
diff --git a/squashfs-tools/fnmatch_compat.h b/squashfs-tools/fnmatch_compat.h
new file mode 100644
index 0000000..7b4afd8
--- /dev/null
+++ b/squashfs-tools/fnmatch_compat.h
@@ -0,0 +1,32 @@
+#ifndef FNMATCH_COMPAT
+#define FNMATCH_COMPAT
+/*
+ * Squashfs
+ *
+ * Copyright (c) 2015
+ * Phillip Lougher <phillip@squashfs.org.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * fnmatch_compat.h
+ */
+
+#include <fnmatch.h>
+
+#ifndef FNM_EXTMATCH
+#define FNM_EXTMATCH	0
+#endif
+
+#endif
diff --git a/squashfs-tools/mksquashfs.c b/squashfs-tools/mksquashfs.c
index d221c35..4e7cbdd 100644
--- a/squashfs-tools/mksquashfs.c
+++ b/squashfs-tools/mksquashfs.c
@@ -46,7 +46,6 @@
 #include <sys/mman.h>
 #include <pthread.h>
 #include <regex.h>
-#include <fnmatch.h>
 #include <sys/wait.h>
 #include <limits.h>
 #include <ctype.h>
@@ -76,6 +75,7 @@
 #include "read_fs.h"
 #include "restore.h"
 #include "process_fragments.h"
+#include "fnmatch_compat.h"
 
 int delete = FALSE;
 int fd;
diff --git a/squashfs-tools/unsquashfs.c b/squashfs-tools/unsquashfs.c
index 1323dd6..2428baa 100644
--- a/squashfs-tools/unsquashfs.c
+++ b/squashfs-tools/unsquashfs.c
@@ -30,6 +30,7 @@
 #include "xattr.h"
 #include "unsquashfs_info.h"
 #include "stdarg.h"
+#include "fnmatch_compat.h"
 
 #include <sys/sysinfo.h>
 #include <sys/types.h>
diff --git a/squashfs-tools/unsquashfs.h b/squashfs-tools/unsquashfs.h
index ecd0bb4..0edbd25 100644
--- a/squashfs-tools/unsquashfs.h
+++ b/squashfs-tools/unsquashfs.h
@@ -40,7 +40,6 @@
 #include <grp.h>
 #include <time.h>
 #include <regex.h>
-#include <fnmatch.h>
 #include <signal.h>
 #include <pthread.h>
 #include <math.h>