Summary:
Typically most main functions have the signature:
```
int main(int argc, char *argv[])
```
To stick with convention when renaming parameters we should ignore the `argc` and `argv` names even if the parameter style says they should be renamed. This patch addresses this by checking all ParmVarDecls if they form part of a function with a signature that matches main `int name(int argc, char * argv[], (optional char *env[]))`
Reviewers: aaron.ballman, JonasToth, alexfh, hokein
Reviewed By: aaron.ballman
Subscribers: Mordante, merge_guards_bot, xazax.hun, kristof.beyls, cfe-commits
Tags: #clang, #clang-tools-extra
Differential Revision: https://reviews.llvm.org/D73098
Before this patch, readability-identifier-naming contained a significant amount
of logic for (a) checking the style of identifiers, followed by (b) renaming/
applying fix-its. This patch factors out (b) into a separate base class so that
it can be reused by other checks that want to do renaming. This also cleans up
readability-identifier-naming significantly, since now it only needs to be
concerned with the interesting details of (a).
Nathan James