Increase cmake min version to allow symbol hiding (#51)

CMakeLists.txt

-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION 3.14)
 
 # This is used by ASM for ASM compatibility. Include a file that the parent
 # project can pass to set specific compilation flags
@@ -41,8 +41,9 @@ base_add_subdir(Utils)
 target_include_directories(${output_lib} PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/..")
 
 #Various useful defaults.
-# set_target_properties(${output_lib} PROPERTIES CXX_VISIBILITY_PRESET hidden)
+set_target_properties(${output_lib} PROPERTIES CXX_VISIBILITY_PRESET hidden)
 set_target_properties(${output_lib} PROPERTIES C_VISIBILITY_PRESET hidden)
+set_target_properties(${output_lib} PROPERTIES VISIBILITY_INLINES_HIDDEN ON)
 set_target_properties(${output_lib} PROPERTIES C_STANDARD 99)
 set_target_properties(${output_lib} PROPERTIES POSITION_INDEPENDENT_CODE ON)