Add a basic sample to show how native runtime invokes wasm apps in WAMR and how wasm apps invoke native functions. (#207)

* Add printingAdd print time for wamrc, fix posix mmap bug time for wamrc, fixed a posix mmap bug.

Change-Id: Ib6517b8a69cf022a1a6a74efa1f98155aec143bc

* Add a basic sample to show how native runtime invokes wasm app in WAMR, and how wasm app invokes native functions.

Change-Id: I700ae413ad5e9ea04540d5187952305e1ee92d73

samples/basic/build.sh

@@ -0,0 +1,57 @@
+#!/bin/bash
+
+CURR_DIR=$PWD
+WAMR_DIR=${PWD}/../..
+OUT_DIR=${PWD}/out
+
+WASM_APPS=${PWD}/wasm-apps
+
+
+rm -rf ${OUT_DIR}
+mkdir ${OUT_DIR}
+mkdir ${OUT_DIR}/wasm-apps
+
+
+echo "#####################build basic project"
+cd ${CURR_DIR}
+mkdir -p cmake_build
+cd cmake_build
+cmake ..
+make
+if [ $? != 0 ];then
+    echo "BUILD_FAIL basic exit as $?\n"
+    exit 2
+fi
+
+cp -a basic ${OUT_DIR}
+
+echo -e "\n"
+
+echo "#####################build wasm apps"
+
+cd ${WASM_APPS}
+
+for i in `ls *.c`
+do
+APP_SRC="$i"
+OUT_FILE=${i%.*}.wasm
+
+# use WAMR SDK to build out the .wasm binary
+/opt/wasi-sdk/bin/clang     \
+        --target=wasm32 -O0 -z stack-size=4096 -Wl,--initial-memory=65536 \
+        --sysroot=${WAMR_DIR}/wamr-sdk/app/libc-builtin-sysroot  \
+        -Wl,--allow-undefined-file=${WAMR_DIR}/wamr-sdk/app/libc-builtin-sysroot/share/defined-symbols.txt \
+        -Wl,--no-threads,--strip-all,--no-entry -nostdlib \
+        -Wl,--export=generate_float \
+        -Wl,--export=float_to_string \
+        -Wl,--allow-undefined \
+        -o ${OUT_DIR}/wasm-apps/${OUT_FILE} ${APP_SRC}
+
+
+if [ -f ${OUT_DIR}/wasm-apps/${OUT_FILE} ]; then
+        echo "build ${OUT_FILE} success"
+else
+        echo "build ${OUT_FILE} fail"
+fi
+done
+echo "####################build wasm apps done"