Throw errors on failures to set system properties.

Let's turn this on for awhile in master and see what happens
watching the crash reports.

I'd rather not silently ignore errors if possible.

Change-Id: Ia87cf4448df3a5b3f03c1df5c1fd59a204d02036
diff --git a/core/jni/android_os_SystemProperties.cpp b/core/jni/android_os_SystemProperties.cpp
index 406884b..3c4d2bf 100644
--- a/core/jni/android_os_SystemProperties.cpp
+++ b/core/jni/android_os_SystemProperties.cpp
@@ -164,7 +164,7 @@
 
     if (keyJ == NULL) {
         jniThrowException(env, "java/lang/NullPointerException",
-                                "key must not be null.");
+                          "key must not be null.");
         return ;
     }
     key = env->GetStringUTFChars(keyJ, NULL);
@@ -174,15 +174,20 @@
     } else {
         val = env->GetStringUTFChars(valJ, NULL);
     }
-    
+
     err = property_set(key, val);
-    
+
     env->ReleaseStringUTFChars(keyJ, key);
-    
+
     if (valJ != NULL) {
-    	env->ReleaseStringUTFChars(valJ, val);
+        env->ReleaseStringUTFChars(valJ, val);
     }
-} 
+
+    if (err < 0) {
+        jniThrowException(env, "java/lang/RuntimeException",
+                          "failed to set system property");
+    }
+}
 
 static JNINativeMethod method_table[] = {
     { "native_get", "(Ljava/lang/String;)Ljava/lang/String;",