At least on FreeBSD, boost.asio needs POSIX threads

Why this didn't fail on linux is anyone's guess...

Author: LegalizeAdulthood

cmake/FindBoostAsio.cmake

@@ -8,6 +8,8 @@ if(Boost_FOUND)
         target_include_directories(boost-asio INTERFACE ${Boost_INCLUDE_DIRS})
         if(WIN32)
             target_compile_definitions(boost-asio INTERFACE _WIN32_WINNT=0x0601)
+        else()
+            target_link_libraries(boost-asio INTERFACE -lpthread)
         endif()
         add_library(boost::asio ALIAS boost-asio)
     endif()