Boost.System no longer has a library.

--- 178021959c7556b3076557c2b3819bfd943b2f78/CMakeLists.txt	2025-05-14 10:58:21.000000000 +0100
+++ 178021959c7556b3076557c2b3819bfd943b2f78/CMakeLists.txt	2025-08-15 06:25:08.725586730 +0100
@@ -169,7 +169,7 @@
     endif()
 endif()
 
-set(boost_libs filesystem program_options iostreams system)
+set(boost_libs filesystem program_options iostreams)
 if (Threads_FOUND)
     list(APPEND boost_libs thread)
 endif()
--- 178021959c7556b3076557c2b3819bfd943b2f78/bba/CMakeLists.txt	2025-05-15 00:13:27.000000000 +0100
+++ 178021959c7556b3076557c2b3819bfd943b2f78/bba/CMakeLists.txt	2025-08-15 06:28:49.477980718 +0100
@@ -4,8 +4,7 @@
 set(CMAKE_CXX_STANDARD 17)
 
 find_package(Boost REQUIRED COMPONENTS
-    program_options
-    system)
+    program_options)
 
 add_executable(bbasm
     main.cc)