path_glob: only match a file for a single pattern

[jeanlauliac]

The idea is to match patterns in the order of their declaration, to allow matching specific files into a single pattern. Take the following extract of an hypothetical updfile.json:

  "source_patterns": [
    "src/(system/io).cpp",
    "src/(**/*).cpp",
  ],

In this example, if src/system/io.cpp indeed exists, then it would be matched by pattern 0, but not by pattern 1. If people want to use both, then they can specify both sources 0 and 1. This allows people to blacklist specific files, or reserve them for a special use. On the downside, this force people to deduplicate patterns, make sure they don't overlap unexpectedly.

I want this feature is to be able to compile an app with a different io.cpp implementation for unit tests (a mock filesytem).