Don't build adb for sdk only builds

Change-Id: I0c56213e81a889fd3a7c5e72c4a6e63544a2a3bd
Signed-off-by: Benoit Goby <benoit@android.com>
diff --git a/adb/Android.mk b/adb/Android.mk
index fe6fbed..df96d58 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -157,6 +157,7 @@
 # adb host tool for device-as-host
 # =========================================================
 ifneq ($(TARGET_SIMULATOR),true)
+ifneq ($(SDK_ONLY),true)
 include $(CLEAR_VARS)
 
 LOCAL_LDLIBS := -lrt -lncurses -lpthread
@@ -194,3 +195,4 @@
 
 include $(BUILD_EXECUTABLE)
 endif
+endif