LibPDF: Add a CFF_DEBUG toggle

I'd like to put some debug prints behind this soon.

No behavior change.

Meta/CMake/all_the_debug_macros.cmake

@@ -14,6 +14,7 @@ set(BXVGA_DEBUG ON)
 set(CACHE_DEBUG ON)
 set(CALLBACK_MACHINE_DEBUG ON)
 set(CANVAS_RENDERING_CONTEXT_2D_DEBUG ON)
+set(CFF_DEBUG ON)
 set(CMAKE_DEBUG ON)
 set(COMMIT_DEBUG ON)
 set(COMPOSE_DEBUG ON)

Meta/gn/secondary/AK/BUILD.gn

@@ -243,6 +243,7 @@ write_cmake_config("ak_debug_gen") {
     "CACHE_DEBUG=",
     "CALLBACK_MACHINE_DEBUG=",
     "CANVAS_RENDERING_CONTEXT_2D_DEBUG=",
+    "CFF_DEBUG=",
     "CMAKE_DEBUG=",
     "COMPOSE_DEBUG=",
     "COPY_DEBUG=",