Drease memory requirement of sample littlevgl wasm app by 64KB(a page)

samples/littlevgl/README.md

@@ -75,7 +75,7 @@ https://docs.zephyrproject.org/latest/getting_started/index.html</br>
     However, nucleo_f767zi is almost the same as nucleo_f746zg, except FLASH and SRAM size.
     So we changed the DTS setting of nucleo_f746zg boards for a workaround.</br>
 
-    `Modify zephyr/dts/arm/st/f7/stm32f746xg.dtsi, change DT_SIZE_K(320) to DT_SIZE_K(512)`</br>
+    `Modify zephyr/dts/arm/st/f7/stm32f746Xg.dtsi, change DT_SIZE_K(320) to DT_SIZE_K(512)`</br>
     `mkdir build && cd build`</br>
     `source ../../../../zephyr-env.sh`</br>
     `cmake -GNinja -DBOARD=nucleo_f746zg ..`</br>

samples/littlevgl/vgl-wasm-runtime/src/platform/linux/iwasm_main.c

@@ -342,7 +342,7 @@ static host_interface interface = { .send = uart_send, .destroy = uart_destroy }
 
 #endif
 
-static char global_heap_buf[1024 * 1024] = { 0 };
+static char global_heap_buf[390 * 1024] = { 0 };
 
 static void showUsage()
 {

samples/littlevgl/vgl-wasm-runtime/src/platform/zephyr/iwasm_main.c

@@ -82,7 +82,7 @@ void host_destroy()
 host_interface interface = { .init = host_init, .send =
         host_send, .destroy = host_destroy };
 timer_ctx_t timer_ctx;
-static char global_heap_buf[ 498*1024] = { 0 };
+static char global_heap_buf[434 * 1024] = { 0 };
 extern void display_init(void);
 int iwasm_main()
 {

samples/littlevgl/wasm-apps/Makefile_wasm_app

@@ -50,6 +50,6 @@ SRCS += ../../../core/iwasm/lib/app-libs/base/timer.c
 all: 
 	@$(CC) $(CFLAGS) $(SRCS) \
     -s WASM=1 -s SIDE_MODULE=1 -s ASSERTIONS=1 -s STACK_OVERFLOW_CHECK=2 \
-    -s TOTAL_MEMORY=131072 -s TOTAL_STACK=8096 \
+    -s TOTAL_MEMORY=65536 -s TOTAL_STACK=8096 \
     -s "EXPORTED_FUNCTIONS=['_on_init', '_on_request', '_on_sensor_event', '_on_timer_callback']" \
     -o ui_app.wasm