kernel: Allowing reducing exports

Now that an API has been defined, remove the override for symbol
visibility of the library. It is now possible to build the library with
reduced exports.

Author: TheCharlatan

src/kernel/CMakeLists.txt

@@ -96,16 +96,6 @@ target_link_libraries(bitcoinkernel
 
 target_include_directories(bitcoinkernel PRIVATE $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/src/leveldb/include>)
 
-# libbitcoinkernel requires default symbol visibility, explicitly
-# specify that here so that things still work even when user
-# configures with -DREDUCE_EXPORTS=ON
-#
-# Note this is a quick hack that will be removed as we
-# incrementally define what to export from the library.
-set_target_properties(bitcoinkernel PROPERTIES
-  CXX_VISIBILITY_PRESET default
-)
-
 # Add a convenience libbitcoinkernel target as a synonym for bitcoinkernel.
 add_custom_target(libbitcoinkernel)
 add_dependencies(libbitcoinkernel bitcoinkernel)