Implement multi-module feature and bulk-memory feature (#271)

Refine wasm loader and aot loader
Fix potential issue of os_mmap/os_munmap
Update document

samples/multi-module/wasm-apps/CMakeLists.txt

@@ -0,0 +1,41 @@
+cmake_minimum_required(VERSION 2.8)
+project(wasm-apps)
+
+set(CMAKE_VERBOSE_MAKEFILE on)
+
+set(WAMR_ROOT_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
+set(CLANG_COMMAND "/opt/wasi-sdk/bin/clang")
+
+set(CLANG_FLAGS --target=wasm32 -nostdlib)
+set(CLANG_FLAGS ${CLANG_FLAGS} -Wl,--no-entry,--allow-undefined,--export-all)
+
+set(SOURCE_A ${CMAKE_CURRENT_SOURCE_DIR}/mA.c)
+add_custom_command(
+  OUTPUT mA.wasm
+  COMMENT "Transform mA.C to mA.WASM"
+  COMMAND ${CLANG_COMMAND} ${CLANG_FLAGS} -o mA.wasm ${SOURCE_A}
+  DEPENDS ${SOURCE_A}
+  VERBATIM
+)
+
+set(SOURCE_B ${CMAKE_CURRENT_SOURCE_DIR}/mB.c)
+add_custom_command(
+  OUTPUT mB.wasm
+  COMMENT "Transform mB.C to mB.WASM"
+  COMMAND ${CLANG_COMMAND} ${CLANG_FLAGS} -o mB.wasm ${SOURCE_B}
+  DEPENDS ${SOURCE_B}
+  VERBATIM
+)
+
+set(SOURCE_C ${CMAKE_CURRENT_SOURCE_DIR}/mC.c)
+add_custom_command(
+  OUTPUT mC.wasm
+  COMMENT "Transform mC.C to mC.WASM"
+  COMMAND ${CLANG_COMMAND} ${CLANG_FLAGS} -o mC.wasm ${SOURCE_C}
+  DEPENDS ${SOURCE_C}
+  VERBATIM
+)
+
+add_custom_target(wasm-modules ALL
+  DEPENDS mA.wasm mB.wasm mC.wasm
+)

samples/multi-module/wasm-apps/mA.c

@@ -0,0 +1,5 @@
+int
+A()
+{
+    return 10;
+}

samples/multi-module/wasm-apps/mB.c

@@ -0,0 +1,16 @@
+__attribute__((import_module("mA")))
+__attribute__((import_name("A"))) extern int
+A();
+
+int
+B()
+{
+    return 11;
+}
+
+int
+call_A()
+{
+    return A();
+}
+

samples/multi-module/wasm-apps/mC.c

@@ -0,0 +1,25 @@
+__attribute__((import_module("mA")))
+__attribute__((import_name("A"))) extern int
+A();
+
+__attribute__((import_module("mB")))
+__attribute__((import_name("B"))) extern int
+B();
+
+int
+C()
+{
+    return 12;
+}
+
+int
+call_A()
+{
+    return A();
+}
+
+int
+call_B()
+{
+    return B();
+}