stored: add support for glusterfs 6.0

GlusterFS 6.0 contains a new glfs_truncate() call with 4 parameters.
Bareos (18.2+) detect this and add a macro supporting both versions. For
autoconf we simply check for GLFS_STAT_ALL that was introduced in v6.0
and implement the same workaround as for 18.2+.

src/stored/backends/gfapi_device.h

@@ -30,6 +30,14 @@
 
 #include <api/glfs.h>
 
+/*
+ * GLFS_STAT_ALL is introduced in v6.0 which also introduces two additional
+ * parameters for glfs_truncate()
+ */
+#if defined GLFS_STAT_ALL
+#define glfs_ftruncate(fd, offset) glfs_ftruncate(fd, offset, NULL, NULL)
+#endif
+
 class gfapi_device: public DEVICE {
 private:
    char *m_gfapi_configstring;