mu3hook/unity.c: hook Unity plugin DLLs

- Unity loads plugin DLLs and Mono dynamically.

- Ongeki uses Criware for videos so hook the Criware plugin DLL so the
  path hooks load the videos from the hooked paths.

mu3hook/meson.build

@@ -24,5 +24,7 @@ shared_library(
         'dllmain.c',
         'io4.c',
         'io4.h',
+        'unity.h',
+        'unity.c',
     ],
 )