Stop defining local "unused" macros now this is C++.

Bug: N/A
Test: builds, boots
Change-Id: I3eb075d5003fa7cdc6690f4af29a296e22be257c
diff --git a/libcutils/trace-host.cpp b/libcutils/trace-host.cpp
index 05842cd..d47cc18 100644
--- a/libcutils/trace-host.cpp
+++ b/libcutils/trace-host.cpp
@@ -16,21 +16,17 @@
 
 #include <cutils/trace.h>
 
-#ifndef __unused
-#define __unused __attribute__((__unused__))
-#endif
-
 atomic_bool             atrace_is_ready      = ATOMIC_VAR_INIT(true);
 int                     atrace_marker_fd     = -1;
 uint64_t                atrace_enabled_tags  = 0;
 
-void atrace_set_debuggable(bool debuggable __unused) { }
-void atrace_set_tracing_enabled(bool enabled __unused) { }
+void atrace_set_debuggable(bool /*debuggable*/) {}
+void atrace_set_tracing_enabled(bool /*enabled*/) {}
 void atrace_update_tags() { }
 void atrace_setup() { }
-void atrace_begin_body(const char* name __unused) { }
+void atrace_begin_body(const char* /*name*/) {}
 void atrace_end_body() { }
-void atrace_async_begin_body(const char* name __unused, int32_t cookie __unused) { }
-void atrace_async_end_body(const char* name __unused, int32_t cookie __unused) { }
-void atrace_int_body(const char* name __unused, int32_t value __unused) { }
-void atrace_int64_body(const char* name __unused, int64_t value __unused) { }
+void atrace_async_begin_body(const char* /*name*/, int32_t /*cookie*/) {}
+void atrace_async_end_body(const char* /*name*/, int32_t /*cookie*/) {}
+void atrace_int_body(const char* /*name*/, int32_t /*value*/) {}
+void atrace_int64_body(const char* /*name*/, int64_t /*value*/) {}