chore: add optional dynamic linking to boost::log

When building boost as a dynamic library, during linking, hundreds of
`undefined reference to `boost::log` errors occure. As the default behavior
currently is to statically link against boost::log, it is best to add a new
option that explicitly enables dynamically linking to boost::log. This new
option is called MENDER_USE_DYNAMIC_BOOST_LOG.

Signed-off-by: Adam Duskett <aduskett@gmail.com>

src/common/cmake/boost.cmake

@@ -3,6 +3,10 @@
 find_package(Boost 1.74 COMPONENTS log)
 
 option(MENDER_DOWNLOAD_BOOST "Download Boost if it is not found (Default: OFF)" OFF)
+option(MENDER_USE_DYNAMIC_BOOST_LOG "Link dynamically to boost::log  (Default: OFF)" OFF)
+if(MENDER_USE_DYNAMIC_BOOST_LOG)
+  ADD_DEFINITIONS(-DBOOST_LOG_DYN_LINK)
+endif()
 
 if(NOT MENDER_DOWNLOAD_BOOST AND NOT ${Boost_FOUND})
   message(FATAL_ERROR