Remove thread refcount and remove NaClAppDtor()

src/native_client/src/trusted/service_runtime/arch/x86_64/sel_addrspace_x86_64.c

Index: src/native_client/src/trusted/service_runtime/arch/x86_64/sel_addrspace_x86_64.c
diff --git a/src/native_client/src/trusted/service_runtime/arch/x86_64/sel_addrspace_x86_64.c b/src/native_client/src/trusted/service_runtime/arch/x86_64/sel_addrspace_x86_64.c
index c9e5e3b13cf606304eca4bc2d988ab7320809a7c..1d132af4c400ec01c7039b0a10639b7653ea5811 100644
--- a/src/native_client/src/trusted/service_runtime/arch/x86_64/sel_addrspace_x86_64.c
+++ b/src/native_client/src/trusted/service_runtime/arch/x86_64/sel_addrspace_x86_64.c
@@ -129,22 +129,3 @@ NaClErrorCode NaClMprotectGuards(struct NaClApp *nap) {
 #endif
   return LOAD_OK;
 }
-
-void NaClTeardownMprotectGuards(struct NaClApp *nap) {
-  uintptr_t start_addr;
-
-  if (!nap->guard_pages_initialized) {
-    NaClLog(4, "No guard pages to tear down.\n");
-    return;
-  }
-  start_addr = nap->mem_start;
-
-  /*
-   * No need to undo mprotect, since we're just deallocating back to
-   * the system.
-   */
-  NaCl_page_free((void *) (start_addr - GUARDSIZE),
-                 GUARDSIZE);
-  NaCl_page_free((void *) (start_addr + FOURGIG),
-                 GUARDSIZE);
-}