mprotect system call exposed to the untrusted code.

src/untrusted/nacl/sys_private.c

Index: src/untrusted/nacl/sys_private.c
diff --git a/src/untrusted/nacl/sys_private.c b/src/untrusted/nacl/sys_private.c
index 204ab5f480253b8188bacf80060b2a001c5ef814..e9a3ba67cdb2e53c43148cffcaeb1ca027e5d0a3 100644
--- a/src/untrusted/nacl/sys_private.c
+++ b/src/untrusted/nacl/sys_private.c
@@ -106,6 +106,10 @@ int munmap(void *start, size_t length) {
   return errno_call(NACL_SYSCALL(munmap)(start, length));
 }
 
+int mprotect(void *start, size_t length, int prot) {
+  return errno_call(NACL_SYSCALL(mprotect)(start, length, prot));
+}
+
 int open(char const *pathname, int oflag, ...) {
   mode_t cmode;
   va_list ap;