Updates for SGX 2.17 reproducible build.

Signed-off-by: Zhang Lili <lili.z.zhang@intel.com>

SampleCode/SampleEnclavePCL/Enclave/Enclave.cpp

@@ -40,7 +40,7 @@
  * printf: 
  *   Invokes OCALL to display the enclave buffer to the terminal.
  */
-void printf(const char *fmt, ...)
+int printf(const char *fmt, ...)
 {
     char buf[BUFSIZ] = {'\0'};
     va_list ap;
@@ -48,4 +48,5 @@ void printf(const char *fmt, ...)
     vsnprintf(buf, BUFSIZ, fmt, ap);
     va_end(ap);
     ocall_print_string(buf);
+    return 0;
 }