Enable clang-tidy bugprone-too-small-loop-variable

And fixes for it in the code
6 jobs for too-small-loop-variable in 10 minutes and 17 seconds (queued for 7 seconds)
Status Job ID Name Coverage
  Build
passed #688752
build

00:03:41

passed #688757
build_android

00:02:06

passed #688753
build_clang_libcpp

00:04:10

passed #688756
build_clazy

00:04:28

passed #688755
build_mingw64_fedora

00:03:31

passed #688754
build_ubuntu_16_04

00:05:40