NFC: .clang-tidy: Inherit configs from parents to improve maintainability

In the interests of disabling misc-no-recursion across LLVM (this seems
like a stylistic choice that is not consistent with LLVM's
style/development approach) this NFC preliminary change adjusts all the
.clang-tidy files to inherit from their parents as much as possible.

This change specifically preserves all the quirks of the current configs
in order to make it easier to review as NFC.

I validatad the change is NFC as follows:

for X in `cat ../files.txt`;
do
  mkdir -p ../tmp/$(dirname $X)
  touch $(dirname $X)/blaikie.cpp
  clang-tidy -dump-config $(dirname $X)/blaikie.cpp > ../tmp/$(dirname $X)/after
  rm $(dirname $X)/blaikie.cpp
done

(similarly for the "before" state, without this patch applied)

for X in `cat ../files.txt`;
do
  echo $X
  diff \
    ../tmp/$(dirname $X)/before \
    <(cat ../tmp/$(dirname $X)/after \
      | sed -e "s/,readability-identifier-naming\(.*\),-readability-identifier-naming/\1/" \
      | sed -e...