Remove unused systemTime() and include utils/Timers.h.

Remove a systemTime() function from power/power.c that
doesn't appear to be called anywhere, and make several
audio/ files explicitly include utils/Timers.h for the
libutils version of systemTime(). (They appear to have been
transitively getting it via utils/threads.h's include of
utils/Condition.h.)

Change-Id: I432bb1cf1100f5829df307a146076acf035a0bdc

audio/A2dpAudioInterface.cpp

@@ -20,6 +20,7 @@
 #define LOG_TAG "A2dpAudioInterface"
 #include <utils/Log.h>
 #include <utils/String8.h>
+#include <utils/Timers.h>
 
 #include "A2dpAudioInterface.h"
 #include "audio/liba2dp.h"

audio/AudioPolicyManagerBase.cpp

@@ -36,6 +36,7 @@
 
 #include <cutils/properties.h>
 #include <utils/Log.h>
+#include <utils/Timers.h>
 
 #include <hardware/audio.h>
 #include <hardware/audio_effect.h>

power/power.c

@@ -19,8 +19,6 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <unistd.h>
-#include <sys/time.h>
-#include <time.h>
 #include <errno.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -51,14 +49,6 @@ static int g_initialized = 0;
 static int g_fds[OUR_FD_COUNT];
 static int g_error = 1;
 
-static int64_t systemTime()
-{
-    struct timespec t;
-    t.tv_sec = t.tv_nsec = 0;
-    clock_gettime(CLOCK_MONOTONIC, &t);
-    return t.tv_sec*1000000000LL + t.tv_nsec;
-}
-
 static int
 open_file_descriptors(const char * const paths[])
 {