Compilation error if C files are found in a sub-folder

[frahugo]

Let's say I have the following directory structure:

example/
├── Rakefile
├── example-0.0.1.gem
├── example.gemspec
├── ext
│   ├── Rakefile
│   ├── example.c
│   └── utils
│       └── utils.c
└── lib
    └── example
        └── example.rb

When installing the gem, I get the following error:

Don't know how to build task 'x86_64-darwin/utils'

Tasks: TOP => default => x86_64-darwin/libexample.bundle => x86_64-darwin/utils/utils.o
(See full trace by running task with --trace)

[ghost]

Should be fixed now. Thanks!