Clean up use of HAVE_ANDROID_OS

HAVE_ANDROID_OS was defined as "1" for targets, but never defined as "0"
for non-targets. Changing them to #ifdef should be safe and matches
all the other uses of HAVE_ANDROID_OS throughout the system.

Change-Id: I82257325a8ae5e4e4371ddfc4dbf51cea8ea0abb
diff --git a/libs/utils/SystemClock.cpp b/libs/utils/SystemClock.cpp
index 2bdc0ce..062e6d7 100644
--- a/libs/utils/SystemClock.cpp
+++ b/libs/utils/SystemClock.cpp
@@ -19,7 +19,7 @@
  * System clock functions.
  */
 
-#if HAVE_ANDROID_OS
+#ifdef HAVE_ANDROID_OS
 #include <linux/ioctl.h>
 #include <linux/rtc.h>
 #include <utils/Atomic.h>
@@ -50,7 +50,7 @@
     return -1;
 #else
     struct timeval tv;
-#if HAVE_ANDROID_OS
+#ifdef HAVE_ANDROID_OS
     struct timespec ts;
     int fd;
     int res;
@@ -66,7 +66,7 @@
 
     LOGD("Setting time of day to sec=%d\n", (int) tv.tv_sec);
 
-#if HAVE_ANDROID_OS
+#ifdef HAVE_ANDROID_OS
     fd = open("/dev/alarm", O_RDWR);
     if(fd < 0) {
         LOGW("Unable to open alarm driver: %s\n", strerror(errno));
@@ -106,7 +106,7 @@
  */
 int64_t elapsedRealtime()
 {
-#if HAVE_ANDROID_OS
+#ifdef HAVE_ANDROID_OS
     static int s_fd = -1;
 
     if (s_fd == -1) {