feat: add libffi cmake dependency

CMakeLists.txt

@@ -3,6 +3,7 @@ project(fz-lang
 	LANGUAGES C)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+set(BUILD_SHARED_LIBS OFF)
 add_compile_options(-Wall -Wextra -Werror=implicit-function-declaration)
 
 if (CMAKE_BUILD_TYPE STREQUAL "Debug")
@@ -11,6 +12,13 @@ if (CMAKE_BUILD_TYPE STREQUAL "Debug")
 endif()
 
 include_directories(include)
+include(FetchContent)
+
+FetchContent_Declare(ffi
+	GIT_REPOSITORY "https://git.samsonium.dev/samsonium/libffi.git"
+	GIT_TAG "main"
+)
+FetchContent_MakeAvailable(ffi)
 
 # Compiler
 add_executable(fzc
@@ -56,6 +64,8 @@ add_executable(fz
 	src/vm/fzl_vm_debug.c
 	src/vm/main.c)
 
+target_link_libraries(fz PRIVATE ffi_static dl)
+
 #
 # ========== Tests ==========
 #