Implement 2D graphic API (#87)

* Implement 2D graphic library based on LittlevGL

* Add lvgl license file

samples/gui/build.sh

@@ -0,0 +1,67 @@
+#!/bin/bash
+
+PROJECT_DIR=$PWD
+WAMR_DIR=${PWD}/../..
+OUT_DIR=${PWD}/out
+BUILD_DIR=${PWD}/build
+
+if [ ! -d $BUILD_DIR ]; then
+    mkdir ${BUILD_DIR}
+fi
+
+rm -rf ${OUT_DIR}
+mkdir ${OUT_DIR}
+
+
+cd ${WAMR_DIR}/core/shared-lib/mem-alloc
+if [ ! -d "tlsf" ]; then
+    git clone https://github.com/mattconte/tlsf
+fi
+
+echo "##################### 1. build native-ui-app start#####################"
+cd $BUILD_DIR
+mkdir -p lvgl-native-ui-app
+cd lvgl-native-ui-app
+cmake ${PROJECT_DIR}/lvgl-native-ui-app
+make
+if [ $? != 0 ];then
+    echo "BUILD_FAIL native-ui-app $?\n"
+    exit 2
+fi
+echo $PWD
+cp  lvgl_native_ui_app ${OUT_DIR}
+echo "#####################build native-ui-app success"
+
+echo "#####################build host-tool"
+cd $BUILD_DIR
+mkdir -p host-tool
+cd host-tool
+cmake ${WAMR_DIR}/test-tools/host-tool
+make
+if [ $? != 0 ];then
+        echo "BUILD_FAIL host tool exit as $?\n"
+        exit 2
+fi
+cp host_tool ${OUT_DIR}
+echo "#####################build host-tool success"
+
+
+echo "##################### 2. build littlevgl wasm runtime start#####################"
+cd $BUILD_DIR
+mkdir -p wasm-runtime-wgl
+cd wasm-runtime-wgl
+cmake ${PROJECT_DIR}/wasm-runtime-wgl/linux-build
+make
+cp wasm_runtime_wgl ${OUT_DIR}/
+
+echo "##################### build littlevgl wasm runtime end#####################"
+
+
+echo "##################### 3. build wasm ui app start#####################"
+cd ${PROJECT_DIR}/wasm-apps/wgl
+make
+cp ui_app.wasm ${OUT_DIR}/
+cd ${PROJECT_DIR}/wasm-apps/lvgl-compatible
+make
+cp ui_app_lvgl_compatible.wasm ${OUT_DIR}/
+echo "#####################  build wasm ui app end#####################"