build: fix build on musl

Closes: https://github.com/containers/fuse-overlayfs/issues/145

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

fuse_overlayfs_error.h

@@ -0,0 +1,40 @@
+/* fuse-overlayfs: Overlay Filesystem in Userspace
+
+   Copyright (C) 2019 Red Hat Inc.
+
+   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 3 of the License, 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef FUSE_OVERLAYFS_ERROR_H
+# define FUSE_OVERLAYFS_ERROR_H
+
+# include <config.h>
+
+# ifdef HAVE_ERROR_H
+#  include <error.h>
+# else
+#  define error(status, errno, fmt, ...) do {                           \
+    if (errno == 0)                                                     \
+      fprintf (stderr, "fuse-overlayfs: " fmt "\n", ##__VA_ARGS__);     \
+    else                                                                \
+      {                                                                 \
+        fprintf (stderr, "fuse-overlayfs: " fmt, ##__VA_ARGS__);        \
+        fprintf (stderr, ": %s\n", strerror (errno));                   \
+      }                                                                 \
+    if (status)                                                         \
+      exit (status);                                                    \
+  } while(0)
+# endif
+
+#endif

main.c

@@ -43,21 +43,7 @@
 # include <sys/sendfile.h>
 #endif
 
-#ifdef HAVE_ERROR_H
-# include <error.h>
-#else
-# define error(status, errno, fmt, ...) do {                           \
-    if (errno == 0)                                                     \
-      fprintf (stderr, "fuse-overlayfs: " fmt "\n", ##__VA_ARGS__);     \
-    else                                                                \
-      {                                                                 \
-        fprintf (stderr, "fuse-overlayfs: " fmt, ##__VA_ARGS__);        \
-        fprintf (stderr, ": %s\n", strerror (errno));                   \
-      }                                                                 \
-    if (status)                                                         \
-      exit (status);                                                    \
-  } while(0)
-#endif
+#include <fuse_overlayfs_error.h>
 
 #include <inttypes.h>
 #include <fcntl.h>

plugin-manager.c

@@ -19,7 +19,7 @@
 #include <config.h>
 #include <plugin.h>
 #include <stdlib.h>
-#include <error.h>
+#include <fuse_overlayfs_error.h>
 #include <errno.h>
 #include <string.h>