.clang-tidy: temporarily disable misc-const-correctness

This is a relatively new check added to clang-tidy by 46ae26e7eb70
("[clang-tidy] implement new check 'misc-const-correctness' to add
'const' to unmodified variables", 2022-07-24).  Currently the code
base doesn't follow the practice of declaring variables `const`
where possible, which makes the check quite noisy, so disable it for
now.

Author: svenvh

.clang-tidy

@@ -4,6 +4,7 @@ Checks: |
   llvm-*,
   -llvm-header-guard,
   misc-*,
+  -misc-const-correctness,
   -misc-no-recursion,
   -misc-non-private-member-variables-in-classes,
   -misc-unused-parameters,
@@ -12,6 +13,7 @@ WarningsAsErrors: |
   llvm-*,
   -llvm-header-guard,
   misc-*,
+  -misc-const-correctness,
   -misc-no-recursion,
   -misc-non-private-member-variables-in-classes,
   -misc-unused-parameters,