Allow projects to exclude from libcrt_builtins

Some projects can't be built with libcrt_builtins yet.

Bug: 29275768
Test: m checkbuild
Change-Id: I52805f5dece6395024683d07809c4b8905dab631
Merged-In: I52805f5dece6395024683d07809c4b8905dab631
(cherry picked from commit 2a401bea9e4a0f4d5f5978e244feec2a7b125ddf)
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 3a17604..64caa18 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -185,6 +185,7 @@
 LOCAL_NO_DEFAULT_COMPILER_FLAGS:=
 LOCAL_NO_FPIE :=
 LOCAL_NO_LIBGCC:=
+LOCAL_NO_LIBCRT_BUILTINS:=
 LOCAL_NO_NOTICE_FILE:=
 LOCAL_NO_PIC:=
 LOCAL_NOSANITIZE:=
diff --git a/core/executable_internal.mk b/core/executable_internal.mk
index 10ed913..c28c144 100644
--- a/core/executable_internal.mk
+++ b/core/executable_internal.mk
@@ -36,7 +36,11 @@
 endif
 
 # Define PRIVATE_ variables from global vars
+ifeq ($(LOCAL_NO_LIBCRT_BUILTINS),true)
+my_target_libcrt_builtins :=
+else
 my_target_libcrt_builtins := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)LIBCRT_BUILTINS)
+endif
 ifeq ($(LOCAL_NO_LIBGCC),true)
 my_target_libgcc :=
 else
diff --git a/core/shared_library_internal.mk b/core/shared_library_internal.mk
index 8e2ed3a..44bb020 100644
--- a/core/shared_library_internal.mk
+++ b/core/shared_library_internal.mk
@@ -34,7 +34,11 @@
 include $(BUILD_SYSTEM)/dynamic_binary.mk
 
 # Define PRIVATE_ variables from global vars
+ifeq ($(LOCAL_NO_LIBCRT_BUILTINS),true)
+my_target_libcrt_builtins :=
+else
 my_target_libcrt_builtins := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)LIBCRT_BUILTINS)
+endif
 ifeq ($(LOCAL_NO_LIBGCC),true)
 my_target_libgcc :=
 else