build: make: use -Wl,-z,separate-code w/ -Wl,--execute-only

Also, prefer
-Wl,--execute-only
rather than
-Wl,-execute-only

Bug: 139945549
Bug: 146144180
Test: m
Change-Id: I4a07978c7a84a0a7e841b9e059305b0f443d0e95
Suggested-by: Ryan Prichard <rprichard@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

core/binary.mk

@@ -109,7 +109,7 @@ ifneq ($(strip $(ENABLE_XOM)),false)
     ifeq ($(strip $(my_xom)),true)
       ifeq (arm64,$(TARGET_$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH))
         ifeq ($(my_use_clang_lld),true)
-          my_ldflags += -Wl,-execute-only
+          my_ldflags += -Wl,--execute-only -Wl,-z,separate-code
         endif
       endif
     endif