[linter] Sanitize the headers include guard

Summary: Replace with an underscore any non alphanumerical character. This will ensure that paths like /src/foo-bar/baz.h doesn't generate an invalid include guard.

Test Plan: Create a directory in src with some non alphanum char, and a header.h file in that directory. Check the linter returns a sanitizer include guard.

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Subscribers: sdulfari

Differential Revision: https://reviews.bitcoinabc.org/D11812