This reverts commit f816e66.

Reverts #13848

Unfortunately, this breaks the indexer for many projects that are still
building on clang 18 with errors like:

```
Step #23: fatal error: too many errors emitted, stopping now [-ferror-limit=]
Step #23:       |                                         ^~~~~~~~~~~~
Step #23:   422 |     return (__m64)__builtin_ia32_paddsb((__v8qi)__m1, (__v8qi)__m2);
Step #23: /usr/local/lib/clang/18/include/mmintrin.h:422:41: error: cannot initialize a parameter of type 'unsigned int' with an rvalue of type '__v8qi' (vector of 8 'char' values)
Step #23:       |                   ^~~~~~~~~~~~~~~~~~~~~
Step #23:   422 |     return (__m64)__builtin_ia32_paddsb((__v8qi)__m1, (__v8qi)__m2);
Step #23: /usr/local/lib/clang/18/include/mmintrin.h:422:19: error: use of undeclared identifier '__builtin_ia32_paddsb'; did you mean '__builtin_ia32_kaddsi'?
Step #23:       |                   ^~~~~~~~~~~~~~~~~~~~
Step #23:   400 |     return (__m64)__builtin_ia32_paddd((__v2si)__m1, (__v2si)__m2);
Step #23: /usr/local/lib/clang/18/include/mmintrin.h:400:19: error: use of undeclared identifier '__builtin_ia32_paddd'
Step #23:       |                   ^~~~~~~~~~~~~~~~~~~~
Step #23:   379 |     return (__m64)__builtin_ia32_paddw((__v4hi)__m1, (__v4hi)__m2);
Step #23: /usr/local/lib/clang/18/include/mmintrin.h:379:19: error: use of undeclared identifier '__builtin_ia32_paddw'
Step #23:       |                   ^~~~~~~~~~~~~~~~~~~~
Step #23:   358 |     return (__m64)__builtin_ia32_paddb((__v8qi)__m1, (__v8qi)__m2);
Step #23: /usr/local/lib/clang/18/include/mmintrin.h:358:19: error: use of undeclared identifier '__builtin_ia32_paddb'
```

Addressing projects that have errors like the following:

```sh
Step #23 - "compile-libfuzzer-address-x86_64": �[1m/usr/local/lib/clang/21/include/fuzzer/FuzzedDataProvider.h:206:22: �[0m�[0;1;31merror: �[0m�[1mno template named 'is_integral_v' in namespace 'std'; did you mean 'is_integral'?�[0m
Step #23 - "compile-libfuzzer-address-x86_64":   206 |   �[0;34mstatic_assert�[0m(std::is_integral_v<T>, �[0;32m"An integral type is required."�[0m);�[0m
Step #23 - "compile-libfuzzer-address-x86_64":       | �[0;1;32m                ~~~~~^
Step #23 - "compile-libfuzzer-address-x86_64": �[0m�[1m/usr/local/bin/../include/c++/v1/__type_traits/is_integral.h:25:35: �[0m�[0;1;36mnote: �[0m'is_integral' declared here�[0m
Step #23 - "compile-libfuzzer-address-x86_64":    25 | �[0;34mstruct�[0m _LIBCPP_NO_SPECIALIZATIONS is_integral : _BoolConstant<�[0;34m__is_integral�[0m(_Tp)> {};�[0m
Step #23 - "compile-libfuzzer-address-x86_64":       | �[0;1;32m                                  ^
Step #23 - "compile-libfuzzer-address-x86_64": �[0mIn file included from /src/buffer_fuzzer.cc:19:
Step #23 - "compile-libfuzzer-address-x86_64": �[1m/usr/local/lib/clang/21/include/fuzzer/FuzzedDataProvider.h:206:38: �[0m�[0;1;31merror: �[0m�[1mexpected '(' for function-style cast or type construction�[0m
Step #23 - "compile-libfuzzer-address-x86_64":   206 |   �[0;34mstatic_assert�[0m(std::is_integral_v<T>, �[0;32m"An integral type is required."�[0m);�[0m
Step #23 - "compile-libfuzzer-address-x86_64":       | �[0;1;32m                ~~~~~~~~~~~~~~~~~~~~~^
Step #23 - "compile-libfuzzer-address-x86_64": �[0m�[1m/usr/local/lib/clang/21/include/fuzzer/FuzzedDataProvider.h:274:22: �[0m�[0;1;31merror: �[0m�[1mno template named 'is_floating_point_v' in namespace 'std'; did you mean 'is_floating_point'?�[0m
Step #23 - "compile-libfuzzer-address-x86_64":   274 |   �[0;34mstatic_assert�[0m(std::is_floating_point_v<T>,�[0m
```

From
#13848 (comment)

Ref #13915

---------

Signed-off-by: David Korczynski <david@adalogics.com>