In my use case, I have a very large hierarchy of libraries (>1000) that need to be statically linked together. All the .pc files for this hierarchy are automatically generated by us (internal libraries) and thus we control how they look.

I notice that during the running of `pkg-config` it spends a large amount of time checking for conflicts which is not a feature we use in our automatic generation. Therefore, I would like the ability to disable this.

I can see two approaches whilst implementing this and would like to discuss which is more favourable.

1) Add a command-line option to disable conflict checking (`--disable-conflicts` or similar). Then this flag can simply be checked before running `recursive_fill_list` and users have explicitly opt-ed out.

2) Make `pkg-config` more intelligent and detect usage of the `conflicts` feature during hierarchy parsing. This has the benefit of speeding up all users of `pkg-config` by detecting whether the conflicts feature has been used and would skip the step of checking for them. However, this would inhibit users who specifically want to inhibit conflict checking in use-cases where they do not govern the generation of all PC files. Additionally, it is a little more invasive in terms of code (the file parsing routine would be have to be extended to produce and output variable for this use-case).