Frameworks/base: Wall Werror in drm

Turn on -Wall -Werror in drm/jni. Fix warnings.

Change-Id: If24fec45fbb737af593ddadfa473548dfa583e0b

drm/jni/Android.mk

@@ -39,8 +39,8 @@ LOCAL_C_INCLUDES += \
     $(TOP)/frameworks/av/include \
     $(TOP)/libcore/include
 
-
-
 LOCAL_MODULE_TAGS := optional
 
+LOCAL_CFLAGS += -Wall -Werror -Wunused -Wunreachable-code
+
 include $(BUILD_SHARED_LIBRARY)

drm/jni/android_drm_DrmManagerClient.cpp

@@ -381,7 +381,8 @@ static jobjectArray android_drm_DrmManagerClient_getAllSupportInfo(
 }
 
 static void android_drm_DrmManagerClient_installDrmEngine(
-            JNIEnv* env, jobject thiz, jint uniqueId, jstring engineFilePath) {
+            JNIEnv* /* env */, jobject /* thiz */, jint /* uniqueId */,
+            jstring /* engineFilePath */) {
     ALOGV("installDrmEngine - Enter");
     //getDrmManagerClient(env, thiz)
     //  ->installDrmEngine(uniqueId, Utility::getStringValue(env, engineFilePath));
@@ -776,7 +777,7 @@ static int registerNativeMethods(JNIEnv* env) {
     return result;
 }
 
-jint JNI_OnLoad(JavaVM* vm, void* reserved) {
+jint JNI_OnLoad(JavaVM* vm, void* /* reserved */) {
     JNIEnv* env = NULL;
     jint result = -1;