Define atrace_* functions for both target and host.

This change defines atrace_* functions for the host that act as
no-ops, which makes it easier to add tracing in ART.

Change-Id: I89397e83986686a2b6a6f245c25017eb379081b1
diff --git a/libcutils/Android.mk b/libcutils/Android.mk
index d890319..9f32307 100644
--- a/libcutils/Android.mk
+++ b/libcutils/Android.mk
@@ -59,7 +59,8 @@
         sockets.c \
 
     commonHostSources += \
-        ashmem-host.c
+        ashmem-host.c \
+        trace-host.c
 
 endif
 
@@ -116,7 +117,7 @@
         partition_utils.c \
         properties.c \
         qtaguid.c \
-        trace.c \
+        trace-dev.c \
         uevent.c \
 
 LOCAL_SRC_FILES_arm += \
diff --git a/libcutils/trace.c b/libcutils/trace-dev.c
similarity index 100%
rename from libcutils/trace.c
rename to libcutils/trace-dev.c
diff --git a/libcutils/trace-host.c b/libcutils/trace-host.c
new file mode 100644
index 0000000..b87e543
--- /dev/null
+++ b/libcutils/trace-host.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2012 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
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <cutils/trace.h>
+
+#ifndef __unused
+#define __unused __attribute__((__unused__))
+#endif
+
+volatile int32_t        atrace_is_ready      = 1;
+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_update_tags() { }
+void atrace_setup() { }
+void atrace_begin_body(const char* name __unused) { }
+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) { }