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

This is a relatively new check added to clang-tidy by 46ae26e
("[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.

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@4dd494e

Author: svenvh

llvm-spirv/.clang-tidy

@@ -1,5 +1,23 @@
-Checks: '-*,clang-diagnostic-*,llvm-*,misc-*,-misc-no-recursion,-misc-unused-parameters,readability-identifier-naming,-llvm-header-guard'
-WarningsAsErrors: 'llvm-*,misc-*,-misc-no-recursion,-misc-unused-parameters,readability-identifier-naming,-llvm-header-guard'
+Checks: |
+  -*,
+  clang-diagnostic-*,
+  llvm-*,
+  -llvm-header-guard,
+  misc-*,
+  -misc-const-correctness,
+  -misc-no-recursion,
+  -misc-non-private-member-variables-in-classes,
+  -misc-unused-parameters,
+  readability-identifier-naming
+WarningsAsErrors: |
+  llvm-*,
+  -llvm-header-guard,
+  misc-*,
+  -misc-const-correctness,
+  -misc-no-recursion,
+  -misc-non-private-member-variables-in-classes,
+  -misc-unused-parameters,
+  readability-identifier-naming
 CheckOptions:
   - key:             readability-identifier-naming.ClassCase
     value:           CamelCase