qemu: Provide non-linux stub for qemuDomainAttachDeviceMknodRecursive

The way we create devices under /dev is highly linux specific.
For instance we do mknod(), mount(), umount(), etc. Some
platforms are even missing some of these functions. Then again,
as declared in qemuDomainNamespaceAvailable(): namespaces are
linux only. Therefore, to avoid obfuscating the code by trying to
make it compile on weird platforms, just provide a non-linux stub
for qemuDomainAttachDeviceMknodRecursive(). At the same time,
qemuDomainAttachDeviceMknodHelper() which actually calls the
non-existent functions is moved under ifdef __linux__ block since
its only caller is in that block too.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>

src/qemu/qemu_domain.c

@@ -8542,6 +8542,8 @@ struct qemuDomainAttachDeviceMknodData {
 };
 
 
+/* Our way of creating devices is highly linux specific */
+#if defined(__linux__)
 static int
 qemuDomainAttachDeviceMknodHelper(pid_t pid ATTRIBUTE_UNUSED,
                                   void *opaque)
@@ -8811,6 +8813,26 @@ qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver,
 }
 
 
+#else /* !defined(__linux__) */
+
+
+static int
+qemuDomainAttachDeviceMknodRecursive(virQEMUDriverPtr driver ATTRIBUTE_UNUSED,
+                                     virDomainObjPtr vm ATTRIBUTE_UNUSED,
+                                     const char *file ATTRIBUTE_UNUSED,
+                                     char * const *devMountsPath ATTRIBUTE_UNUSED,
+                                     size_t ndevMountsPath ATTRIBUTE_UNUSED,
+                                     unsigned int ttl ATTRIBUTE_UNUSED)
+{
+    virReportSystemError(ENOSYS, "%s",
+                         _("Namespaces are not supported on this platform."));
+    return -1;
+}
+
+
+#endif /* !defined(__linux__) */
+
+
 static int
 qemuDomainAttachDeviceMknod(virQEMUDriverPtr driver,
                             virDomainObjPtr vm,