Enable WASI feature, enhance security and add SGX sample (#142)

Change emcc to clang
Refine interpreter to improve perforamnce

test-tools/toolchain/sysroot/include/limits.h

@@ -10,8 +10,22 @@
 extern "C" {
 #endif
 
-
-
+#define CHAR_BIT    8
+#define SCHAR_MIN   -128
+#define SCHAR_MAX   127
+#define UCHAR_MAX   255
+#define CHAR_MIN    0
+#define CHAR_MAX    127
+#define MB_LEN_MAX  1
+#define SHRT_MIN    -32768
+#define SHRT_MAX    +32767
+#define USHRT_MAX   65535
+#define INT_MIN     -32768
+#define INT_MAX     +32767
+#define UINT_MAX    65535
+#define LONG_MIN    -2147483648
+#define LONG_MAX    +2147483647
+#define ULONG_MAX   4294967295
 
 #ifdef __cplusplus
 }