Add missing stdbool.h to sensor.h.

This got hacked into the NDK headers ages ago, but never got
upstreamed to the frameworks.

Test: make checkbuild
Bug: https://github.com/android-ndk/ndk/issues/370
Merged-In: Id38cbc96633c1c61de36996c2dd9e6c2331bd6e7
Change-Id: Id38cbc96633c1c61de36996c2dd9e6c2331bd6e7
diff --git a/include/android/sensor.h b/include/android/sensor.h
index 4a00818..6c12972 100644
--- a/include/android/sensor.h
+++ b/include/android/sensor.h
@@ -48,6 +48,7 @@
  *
  */
 
+#include <stdbool.h>
 #include <sys/types.h>
 
 #include <android/looper.h>