[llvm] [Triple] Add target triple support for CheriotRTOS. (PR #155374)

[Alexander Richardson via llvm-commits]

================
@@ -687,49 +689,50 @@ static Triple::VendorType parseVendor(StringRef VendorName) {
 
 static Triple::OSType parseOS(StringRef OSName) {
   return StringSwitch<Triple::OSType>(OSName)
-    .StartsWith("darwin", Triple::Darwin)
-    .StartsWith("dragonfly", Triple::DragonFly)
-    .StartsWith("freebsd", Triple::FreeBSD)
-    .StartsWith("fuchsia", Triple::Fuchsia)
-    .StartsWith("ios", Triple::IOS)
-    .StartsWith("kfreebsd", Triple::KFreeBSD)
-    .StartsWith("linux", Triple::Linux)
-    .StartsWith("lv2", Triple::Lv2)
-    .StartsWith("macos", Triple::MacOSX)
-    .StartsWith("managarm", Triple::Managarm)
-    .StartsWith("netbsd", Triple::NetBSD)
-    .StartsWith("openbsd", Triple::OpenBSD)
-    .StartsWith("solaris", Triple::Solaris)
-    .StartsWith("uefi", Triple::UEFI)
-    .StartsWith("win32", Triple::Win32)
-    .StartsWith("windows", Triple::Win32)
-    .StartsWith("zos", Triple::ZOS)
-    .StartsWith("haiku", Triple::Haiku)
-    .StartsWith("rtems", Triple::RTEMS)
-    .StartsWith("aix", Triple::AIX)
-    .StartsWith("cuda", Triple::CUDA)
-    .StartsWith("nvcl", Triple::NVCL)
-    .StartsWith("amdhsa", Triple::AMDHSA)
-    .StartsWith("ps4", Triple::PS4)
-    .StartsWith("ps5", Triple::PS5)
-    .StartsWith("elfiamcu", Triple::ELFIAMCU)
-    .StartsWith("tvos", Triple::TvOS)
-    .StartsWith("watchos", Triple::WatchOS)
-    .StartsWith("bridgeos", Triple::BridgeOS)
-    .StartsWith("driverkit", Triple::DriverKit)
-    .StartsWith("xros", Triple::XROS)
-    .StartsWith("visionos", Triple::XROS)
-    .StartsWith("mesa3d", Triple::Mesa3D)
-    .StartsWith("amdpal", Triple::AMDPAL)
-    .StartsWith("hermit", Triple::HermitCore)
-    .StartsWith("hurd", Triple::Hurd)
-    .StartsWith("wasi", Triple::WASI)
-    .StartsWith("emscripten", Triple::Emscripten)
-    .StartsWith("shadermodel", Triple::ShaderModel)
-    .StartsWith("liteos", Triple::LiteOS)
-    .StartsWith("serenity", Triple::Serenity)
-    .StartsWith("vulkan", Triple::Vulkan)
-    .Default(Triple::UnknownOS);
+      .StartsWith("darwin", Triple::Darwin)
----------------
arichardson wrote:

```
❯ git grep -E '^\s*case\s+.+((return.*;)|(break;))$' lib | wc -l
6733
❯ git grep -E '^\s*case\s+.:$' lib | wc -l 
1102
```
It looks like the short case on a line is actually more common than the longer form, so maybe there should be a RFC to update the clang-format style to something like this
```
AllowShortCaseLabelsOnASingleLine: true
AlignConsecutiveShortCaseStatements:
  Enabled: true
  AcrossEmptyLines: true
  AcrossComments: true
  AlignCaseColons: false
```

https://github.com/llvm/llvm-project/pull/155374