feat: Byte-compile and embed builtin Lua modules

FOr now this is only c_libs, but in future more builtin modules will be
written in Lua.

lib/CMakeLists.txt

@@ -34,3 +34,5 @@ install(FILES
     ${CMAKE_CURRENT_BINARY_DIR}/lege_export.hpp
     DESTINATION include/lege
     )
+
+add_subdirectory(modules)

lib/builtins.cpp

@@ -1,8 +1,13 @@
 #include "builtins.hpp"
 
+// Byte-compiled Lua modules
+#include "modules/lmod_c_libs.h"
+
 namespace lege::modules {
 
 void register_builtins(EngineImpl &e) {
+  e.load((const char *)luaJIT_BC_c_libs, luaJIT_BC_c_libs_SIZE, "b",
+         "lege.c_libs");
   e.load(luaopen_lege_log, "lege.log");
   e.load(luaopen_lege_enum, "lege.enum");
   e.load(luaopen_lege_readonly, "lege.readonly");

lib/modules/CMakeLists.txt

@@ -0,0 +1,33 @@
+# Lua modules:
+# These are byte-compiled and embedded in liblege, then preloaded by the library
+function(add_lua_module MODULE_NAME SOURCE_FILE)
+    find_program(LUAJIT luajit)
+    if(NOT LUAJIT)
+        message(FATAL_ERROR "LuaJIT not found")
+    endif()
+
+    set(luajit_compile_opts "-b" "-t" "h")
+
+    if(CMAKE_BUILD_TYPE MATCHES Debug)
+        list(APPEND luajit_compile_opts "-g")
+    else()
+        list(APPEND luajit_compile_opts "-s")
+    endif()
+
+    set(OUTPUT_HEADER "lmod_${MODULE_NAME}.h")
+
+    add_custom_command(
+        OUTPUT ${OUTPUT_HEADER}
+        COMMAND ${LUAJIT}
+        ARGS ${luajit_compile_opts} "${CMAKE_CURRENT_SOURCE_DIR}/${SOURCE_FILE}" "${CMAKE_CURRENT_BINARY_DIR}/${OUTPUT_HEADER}"
+        DEPENDS ${SOURCE_FILE}
+        COMMENT "Byte-compiling Lua module to ${OUTPUT_HEADER}"
+    )
+
+add_custom_target(lmod_${MODULE_NAME} DEPENDS ${OUTPUT_HEADER})
+add_dependencies(lege lmod_${MODULE_NAME})
+endfunction()
+
+foreach(module c_libs)
+    add_lua_module(${module} ${module}.lua)
+endforeach()