cmake: Add boost system library

Signed-off-by: David Shah <dave@ds0.me>

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7bdff61..9af4bb6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -97,7 +97,7 @@
 find_package(Sanitizers)
 
 # List of Boost libraries to include
-set(boost_libs filesystem thread program_options iostreams)
+set(boost_libs filesystem thread program_options iostreams system)
 
 if (BUILD_GUI AND NOT BUILD_PYTHON)
     message(FATAL_ERROR "GUI requires Python to build")