mprotect system call exposed to the untrusted code.

src/untrusted/irt/irt_memory.c

Index: src/untrusted/irt/irt_memory.c
diff --git a/src/untrusted/irt/irt_memory.c b/src/untrusted/irt/irt_memory.c
index dbd8e738b5934809630fcbcc30228b928f52ea05..2eb0583ddf6b25ac5f12b37716c8f846dba8360a 100644
--- a/src/untrusted/irt/irt_memory.c
+++ b/src/untrusted/irt/irt_memory.c
@@ -45,8 +45,13 @@ static int nacl_irt_munmap(void *addr, size_t len) {
   return -NACL_SYSCALL(munmap)(addr, len);
 }
 
+static int nacl_irt_mprotect(void *addr, size_t len, int prot) {
+  return -NACL_SYSCALL(mprotect)(addr, len, prot);
+}
+
 const struct nacl_irt_memory nacl_irt_memory = {
   nacl_irt_sysbrk,
   nacl_irt_mmap,
   nacl_irt_munmap,
+  nacl_irt_mprotect,
 };