[clan-tidy] Fix false positive in bugprone-infinite-loop

The checker bugprone-infinite-loop does not track changes of
variables in the initialization expression of a variable
declared inside the condition of the while statement. This
leads to false positives, similarly to the one in the bug
report https://bugs.llvm.org/show_bug.cgi?id=44618. This
patch fixes this issue by enabling tracking of the variables
of this expression as well.

Differential Revision: https://reviews.llvm.org/D73270

(cherry picked from commit 70f4c6e7)