[clang] fix --unwindlib option doc (#143497)

the values it takes should be `libunwind` and not `unwindlib`.

Author: fee1-dead

clang/include/clang/Driver/Options.td

@@ -6080,7 +6080,7 @@ def stdlibxx_isystem : JoinedOrSeparate<["-"], "stdlib++-isystem">,
   Flags<[NoXarchOption]>, MetaVarName<"<directory>">;
 def unwindlib_EQ : Joined<["-", "--"], "unwindlib=">,
   Visibility<[ClangOption, CC1Option]>,
-  HelpText<"Unwind library to use">, Values<"libgcc,unwindlib,platform">;
+  HelpText<"Unwind library to use">, Values<"libgcc,libunwind,platform">;
 def sub__library : JoinedOrSeparate<["-"], "sub_library">;
 def sub__umbrella : JoinedOrSeparate<["-"], "sub_umbrella">;
 def system_header_prefix : Joined<["--"], "system-header-prefix=">,