[clang-tools-extra] [clang-doc] Use const and constexpr arrays in BitcodeWriter (PR #198066)

[via cfe-commits]

dyung wrote:

Hi @ilovepi, there seem to be a bunch of assertion failures on Windows that I bisected back to this change. Can you take a look?

https://lab.llvm.org/buildbot/#/builders/46/builds/35573

Sample failure:
```
******************** TEST 'Clang Tools :: clang-doc/basic-project.mustache.test' FAILED ********************
Exit Code: 3
Command Output (stdout):
--
# RUN: at line 1
rm -rf Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp && mkdir -p Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/docs Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/build
# executed command: rm -rf 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp'
# note: command had no output on stdout or stderr
# executed command: mkdir -p 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/docs' 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/build'
# note: command had no output on stdout or stderr
# RUN: at line 2
sed 's|$test_dir|Z:/b/llvm-clang-x86_64-sie-win/llvm-project/clang-tools-extra/test/clang-doc|g' Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang-tools-extra\test\clang-doc/Inputs/basic-project/database_template.json > Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/build/compile_commands.json
# executed command: sed 's|$test_dir|Z:/b/llvm-clang-x86_64-sie-win/llvm-project/clang-tools-extra/test/clang-doc|g' 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang-tools-extra\test\clang-doc/Inputs/basic-project/database_template.json'
# note: command had no output on stdout or stderr
# RUN: at line 4
clang-doc --format=html --output=Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/docs --executor=all-TUs Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/build/compile_commands.json
# executed command: clang-doc --format=html '--output=Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/docs' --executor=all-TUs 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\clang\tools\extra\test\clang-doc\Output\basic-project.mustache.test.tmp/build/compile_commands.json'
# .---command stderr------------
# | [1/3] Processing file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang-tools-extra\test\clang-doc\Inputs\basic-project\src\Circle.cpp
# | [2/3] Processing file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang-tools-extra\test\clang-doc\Inputs\basic-project\src\Rectangle.cpp
# | [3/3] Processing file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\clang-tools-extra\test\clang-doc\Inputs\basic-project\src\Calculator.cpp
# | Assertion failed: ToIndex(N) < Storage.size() && "index out of bounds!", file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\include\llvm/ADT/IndexedMap.h, line 61
# | Assertion failed: ToIndex(N) < Storage.size() && "index out of bounds!", file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\include\llvm/ADT/IndexedMap.h, line 61
# | A
# `-----------------------------
# error: command failed with exit status: 3
--
********************
```

https://github.com/llvm/llvm-project/pull/198066