[libc++] Re-enable Clang-tidy checks in the CI (#110026)

Now that we've gained control of our CI docker image again,
we can re-enable the clang-tidy tests.

Author: ldionne

libcxx/include/chrono

@@ -998,7 +998,6 @@ constexpr chrono::year                                  operator ""y(unsigned lo
 #  include <cstdint>
 #  include <stdexcept>
 #  include <string_view>
-#  include <vector>
 #endif
 
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20

libcxx/test/libcxx/clang_tidy.gen.py

@@ -15,7 +15,7 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.header_information import lit_header_restrictions, public_headers
+from libcxx.header_information import lit_header_restrictions, lit_header_undeprecations, public_headers
 
 for header in public_headers:
   print(f"""\
@@ -30,6 +30,7 @@
 // UNSUPPORTED: clang-17
 
 {lit_header_restrictions.get(header, '')}
+{lit_header_undeprecations.get(header, '')}
 
 // TODO: run clang-tidy with modules enabled once they are supported
 // RUN: %{{clang-tidy}} %s --warnings-as-errors=* -header-filter=.* --checks='-*,libcpp-*' --load=%{{test-tools-dir}}/clang_tidy_checks/libcxx-tidy.plugin -- %{{compile_flags}} -fno-modules

libcxx/test/tools/clang_tidy_checks/CMakeLists.txt

@@ -1,6 +1,3 @@
-# TODO: Re-enable the tests once the CI is back under control
-return()
-
 # The find_package changes these variables. This leaves the build in an odd
 # state. Calling cmake a second time tries to write site config information in
 # the system's libc++. Restoring these setting after testing fixes this issue.