[llvm] [LangRef] Adjust the documentation of some fast-math flags. (PR #99557)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `premerge-monolithic-windows` running on `premerge-windows-1` while building `llvm` at step 8 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/35/builds/1608

Here is the relevant piece of the build log for the reference:
```
Step 8 (test-build-unified-tree-check-all) failure: test (failure)
...
[37/125] Linking CXX executable tools\polly\unittests\Flatten\FlattenTests.exe
[38/125] Linking CXX executable tools\flang\unittests\Optimizer\FlangOptimizerTests.exe
[39/125] Linking CXX executable tools\clang\unittests\Sema\SemaTests.exe
[40/125] Linking CXX executable tools\clang\unittests\Rewrite\RewriteTests.exe
[41/125] Linking CXX executable tools\clang\unittests\AST\Interp\InterpTests.exe
[42/125] Linking CXX executable tools\clang\unittests\CrossTU\CrossTUTests.exe
[43/125] Linking CXX executable tools\clang\unittests\ASTMatchers\Dynamic\DynamicASTMatchersTests.exe
[44/125] Linking CXX executable tools\clang\unittests\Analysis\FlowSensitive\ClangAnalysisFlowSensitiveTests.exe
[45/125] Linking CXX executable tools\clang\tools\extra\unittests\clang-tidy\ClangTidyTests.exe
[46/125] Preparing lit tests
FAILED: utils/lit/CMakeFiles/prepare-check-lit 
cmd.exe /C "cd /D C:\ws\buildbot\premerge-monolithic-windows\build\utils\lit && C:\BuildTools\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe -E remove_directory C:/ws/buildbot/premerge-monolithic-windows/build/utils/lit/tests && C:\BuildTools\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe -E copy_directory C:/ws/buildbot/premerge-monolithic-windows/llvm-project/llvm/utils/lit/tests C:/ws/buildbot/premerge-monolithic-windows/build/utils/lit/tests && C:\BuildTools\Common7\IDE\CommonExtensions\Microsoft\CMake\CMake\bin\cmake.exe -E copy C:/ws/buildbot/premerge-monolithic-windows/build/utils/lit/lit.site.cfg C:/ws/buildbot/premerge-monolithic-windows/build/utils/lit/tests"
Error removing directory "C:/ws/buildbot/premerge-monolithic-windows/build/utils/lit/tests".
[47/125] Linking CXX executable tools\clang\unittests\Tooling\Syntax\SyntaxTests.exe
[48/125] Linking CXX executable tools\clang\unittests\StaticAnalyzer\StaticAnalysisTests.exe
[49/125] Linking CXX executable tools\polly\unittests\Support\ISLToolsTests.exe
[50/125] Linking CXX executable tools\clang\unittests\AST\ASTTests.exe
[51/125] Linking CXX executable unittests\CodeGenData\CodeGenDataTests.exe
[52/125] Linking CXX executable unittests\Bitcode\BitcodeTests.exe
[53/125] Linking CXX executable tools\polly\unittests\DeLICM\DeLICMTests.exe
[54/125] Linking CXX executable unittests\DebugInfo\BTF\DebugInfoBTFTests.exe
[55/125] Linking CXX executable tools\clang\unittests\Index\IndexTests.exe
[56/125] Linking CXX executable tools\polly\unittests\ScopPassManager\ScopPassManagerTests.exe
[57/125] Linking CXX executable tools\clang\unittests\ASTMatchers\ASTMatchersTests.exe
[58/125] Linking CXX executable tools\polly\unittests\ScheduleOptimizer\ScheduleOptimizerTests.exe
[59/125] Linking CXX executable tools\clang\unittests\Rename\ClangRenameTests.exe
[60/125] Linking CXX executable unittests\Analysis\AnalysisTests.exe
[61/125] Linking CXX executable tools\clang\unittests\Serialization\SerializationTests.exe
[62/125] Linking CXX executable tools\clang\unittests\Support\ClangSupportTests.exe
[63/125] Linking CXX executable tools\clang\unittests\CodeGen\ClangCodeGenTests.exe
[64/125] Linking CXX executable tools\mlir\unittests\Target\LLVM\MLIRTargetLLVMTests.exe
[65/125] Linking CXX executable tools\clang\unittests\Driver\ClangDriverTests.exe
[66/125] Linking CXX executable tools\clang\unittests\Frontend\FrontendTests.exe
[67/125] Linking CXX executable bin\mlir-capi-pass-test.exe
[68/125] Linking CXX executable bin\mlir-capi-ir-test.exe
[69/125] Linking CXX executable bin\mlir-capi-execution-engine-test.exe
[70/125] Linking CXX executable tools\lld\unittests\AsLibELF\LLDAsLibELFTests.exe
[71/125] Linking CXX executable tools\lld\unittests\AsLibAll\LLDAsLibAllTests.exe
[72/125] Linking CXX executable tools\clang\tools\extra\clangd\unittests\ClangdTests.exe
[73/125] Linking CXX executable unittests\CodeGen\CodeGenTests.exe
[74/125] Linking CXX executable unittests\CodeGen\GlobalISel\GlobalISelTests.exe
[75/125] Linking CXX executable tools\clang\unittests\Interpreter\ClangReplInterpreterTests.exe
[76/125] Linking CXX executable tools\flang\unittests\Frontend\FlangFrontendTests.exe
[77/125] Linking CXX executable tools\clang\unittests\Tooling\ToolingTests.exe
ninja: build stopped: subcommand failed.

```

https://github.com/llvm/llvm-project/pull/99557