external/boost: Visible function type RTTI for Clang -fsanitize=function

Change-Id: I6a1ab01bbe5cd128b132c3f6dde4b520ddb4c373

external/boost/UnpackedTarball_boost.mk

@@ -108,6 +108,7 @@ boost_patches += boost.boost_static_assert_unused_attribute.patch.0
 boost_patches += w4702.patch.0
 
 boost_patches += ubsan.patch.0
+boost_patches += rtti.patch.0
 
 $(eval $(call gb_UnpackedTarball_UnpackedTarball,boost))
 

external/boost/rtti.patch.0

@@ -0,0 +1,20 @@
+--- boost/function/function_base.hpp
++++ boost/function/function_base.hpp
+@@ -97,7 +97,7 @@
+        * object pointers, and a structure that resembles a bound
+        * member function pointer.
+        */
+-      union function_buffer
++      union BOOST_SYMBOL_VISIBLE function_buffer
+       {
+         // For pointers to function objects
+         mutable void* obj_ptr;
+@@ -159,7 +159,7 @@
+       };
+ 
+       // The operation type to perform on the given functor/function pointer
+-      enum functor_manager_operation_type {
++      enum BOOST_SYMBOL_VISIBLE functor_manager_operation_type {
+         clone_functor_tag,
+         move_functor_tag,
+         destroy_functor_tag,