Make it possible to build libhardware.

third_party/hwcplus/include/hardware/hardware.h

 /*
  * Copyright (C) 2008 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
@@ skipping 207 matching lines @@
  * multiple concurrent interfaces and thus 'audio' is the module class
  * and 'primary' or 'a2dp' are module interfaces. This implies that the files
  * providing these modules would be named audio.primary.<variant>.so and
  * audio.a2dp.<variant>.so
  *
  * @return: 0 == success, <0 == error and *module == NULL
  */
 int hw_get_module_by_class(const char *class_id, const char *inst,
                            const struct hw_module_t **module);
 
+/**
+ * Provide a function to handle log messages.
+ */
+typedef int (*hwcplus_log_fn_t)(int prio, const char* tag, const char* msg);
+void hwcplus_set_log_fn(hwcplus_log_fn_t fn);
+
 __END_DECLS
 
 #endif  /* ANDROID_INCLUDE_HARDWARE_HARDWARE_H */