add mutex to App::update, move custom app-glue to git submodule

android/CMakeLists.txt

@@ -7,7 +7,7 @@ cmake_minimum_required(VERSION 3.4.1)
 # build native_app_glue as a static lib
 add_library(
 	app-glue STATIC
-	${ANDROID_NDK}/sources/android/native_app_glue/android_native_app_glue.c
+	../libs/native_app_glue/android_native_app_glue.c
 )
 
 # Specifies a library name, specifies whether the library is STATIC or
@@ -94,7 +94,6 @@ add_library(
 )
 
 target_include_directories(native-lib PRIVATE
-	${ANDROID_NDK}/sources/android/native_app_glue
 	src/main/cpp
 	../src
 	../libs/glm
@@ -106,7 +105,8 @@ target_include_directories(native-lib PRIVATE
 	../libs/poly2tri/poly2tri
 	../libs/base64
 	../libs/sqlite3
-    ../libs/nanort
+	../libs/nanort
+	../libs/native_app_glue
 )
 
 # add lib dependencies