This commit explicitly specifies the matching mode (C library function,
any non-method function, or C++ method) for the `CallDescription`s
constructed in various checkers.
Some code was simplified to use `CallDescriptionSet`s instead of
individual `CallDescription`s.
This change won't cause major functional changes, but isn't NFC because
it ensures that e.g. call descriptions for a non-method function won't
accidentally match a method that has the same name.
Separate commits have already performed this change in other checkers:
- easy cases: e2f1cbae45f81f3cd9a4d3c2bcf69a094eb060fa
- MallocChecker: d6d84b5d1448e4f2e24b467a0abcf42fe9d543e9
- iterator checkers: 06eedffe0d2782922e63cc25cb927f4acdaf7b30
- InvalidPtr checker: 024281d4d26344f9613b9115ea1fcbdbdba23235
... and follow-up commits will handle the remaining checkers.
My goal is to ensure that the call description mode is always explicitly
specified and eliminate (or strongly restrict) the vague "may be either
a method or a simple function" mode that's the current default.
6d64f8e1fe