Cleanup warnings in the NDK build

Summary:
This diff is cleaning up some configurations in the `Android.mk` files
of the native build. Specifically I simplified some of the rules and removed
a duplicate file specification.

Changelog:
Internal - Cleanup warnings in the NDK build

Reviewed By: ShikaSD

Differential Revision: D30220715

fbshipit-source-id: a100953fe977879a6d28cb0a2ef4b3358fb7c774

ReactAndroid/src/main/jni/react/jni/Android.mk

@@ -39,7 +39,7 @@ LOCAL_STATIC_LIBRARIES := libreactnative libcallinvokerholder libruntimeexecutor
 LOCAL_MODULE := reactnativeutilsjni
 
 # Compile all local c++ files.
-LOCAL_SRC_FILES := $(wildcard Cxx*.cpp) $(wildcard J*.cpp) $(wildcard M*.cpp) $(wildcard N*.cpp) $(wildcard P*.cpp) $(wildcard R*.cpp) $(wildcard W*.cpp)
+LOCAL_SRC_FILES := $(wildcard $(LOCAL_PATH)/*.cpp)
 
 ifeq ($(APP_OPTIM),debug)
   # Keep symbols by overriding the strip command invoked by ndk-build.

ReactAndroid/src/main/jni/third-party/libevent/Android.mk

@@ -12,7 +12,6 @@ LOCAL_SRC_FILES := event.c \
 	bufferevent_ratelim.c \
 	bufferevent_sock.c \
 	epoll.c \
-	event.c \
 	evmap.c \
 	evthread.c \
 	evthread_pthread.c \