build: drop unused/redundant `HAVE_WINLDAP_H`

build: drop unused/redundant `HAVE_WINLDAP_H`

Sources did not use it. Autotools used it when checking for the
`winldap` library, which is redundant.

With CMake, detection was broken:
```
Run Build Command(s):/usr/local/Cellar/cmake/3.26.3/bin/cmake -E env VERBOSE=1 /usr/bin/make -f Makefile cmTC_2d8fe/fast && /Library/Developer/CommandLineTools/usr/bin/make  -f CMakeFiles/cmTC_2d8fe.dir/build.make CMakeFiles/cmTC_2d8fe.dir/build
Building C object CMakeFiles/cmTC_2d8fe.dir/HAVE_WINLDAP_H.c.obj
/usr/local/opt/llvm/bin/clang --target=x86_64-w64-mingw32 --sysroot=/usr/local/opt/mingw-w64/toolchain-x86_64 -D_WINSOCKAPI_="" -I/my/quictls/x64-ucrt/usr/include -I/my/zlib/x64-ucrt/usr/include -I/my/brotli/x64-ucrt/usr/include -Wno-unused-command-line-argument   -D_UCRT -DCURL_HIDDEN_SYMBOLS -DHAVE_SSL_SET0_WBIO -DHAS_ALPN -DNGHTTP2_STATICLIB -DNGHTTP3_STATICLIB -DNGTCP2_STATICLIB -DUSE_MANUAL=1  -fuse-ld=lld -Wl,-s -static-libgcc  -lucrt  -Wextra -Wall -pedantic -Wbad-function-cast -Wconversion -Winline -Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wno-long-long -Wno-multichar -Wpointer-arith -Wshadow -Wsign-compare -Wundef -Wunused -Wwrite-strings -Wcast-align -Wdeclaration-after-statement -Wempty-body -Wendif-labels -Wfloat-equal -Wignored-qualifiers -Wno-format-nonliteral -Wno-sign-conversion -Wno-system-headers -Wstrict-prototypes -Wtype-limits -Wvla -Wshift-sign-overflow -Wshorten-64-to-32 -Wdouble-promotion -Wenum-conversion -Wunused-const-variable -Wcomma -Wmissing-variable-declarations -Wassign-enum -Wextra-semi-stmt  -MD -MT CMakeFiles/cmTC_2d8fe.dir/HAVE_WINLDAP_H.c.obj -MF CMakeFiles/cmTC_2d8fe.dir/HAVE_WINLDAP_H.c.obj.d -o CMakeFiles/cmTC_2d8fe.dir/HAVE_WINLDAP_H.c.obj -c /my/curl/bld-cmake-llvm-x64-shared/CMakeFiles/CMakeScratch/TryCompile-3JP6dR/HAVE_WINLDAP_H.c
In file included from /my/curl/bld-cmake-llvm-x64-shared/CMakeFiles/CMakeScratch/TryCompile-3JP6dR/HAVE_WINLDAP_H.c:2:
In file included from /usr/local/opt/mingw-w64/toolchain-x86_64/x86_64-w64-mingw32/include/winldap.h:17:
In file included from /usr/local/opt/mingw-w64/toolchain-x86_64/x86_64-w64-mingw32/include/schnlsp.h:9:
In file included from /usr/local/opt/mingw-w64/toolchain-x86_64/x86_64-w64-mingw32/include/schannel.h:10:
/usr/local/opt/mingw-w64/toolchain-x86_64/x86_64-w64-mingw32/include/wincrypt.h:5041:254: error: unknown type name 'PSYSTEMTIME'
  WINIMPM PCCERT_CONTEXT WINAPI CertCreateSelfSignCertificate (HCRYPTPROV_OR_NCRYPT_KEY_HANDLE hCryptProvOrNCryptKey, PCERT_NAME_BLOB pSubjectIssuerBlob, DWORD dwFlags, PCRYPT_KEY_PROV_INFO pKeyProvInfo, PCRYPT_ALGORITHM_IDENTIFIER pSignatureAlgorithm, PSYSTEMTIME pStartTime, PSYSTEMTIME pEndTime, PCERT_EXTENSIONS pExtensions);
                                                                                                                                                                                                                                                             ^
/usr/local/opt/mingw-w64/toolchain-x86_64/x86_64-w64-mingw32/include/wincrypt.h:5041:278: error: unknown type name 'PSYSTEMTIME'
  WINIMPM PCCERT_CONTEXT WINAPI CertCreateSelfSignCertificate (HCRYPTPROV_OR_NCRYPT_KEY_HANDLE hCryptProvOrNCryptKey, PCERT_NAME_BLOB pSubjectIssuerBlob, DWORD dwFlags, PCRYPT_KEY_PROV_INFO pKeyProvInfo, PCRYPT_ALGORITHM_IDENTIFIER pSignatureAlgorithm, PSYSTEMTIME pStartTime, PSYSTEMTIME pEndTime, PCERT_EXTENSIONS pExtensions);
                                                                                                                                                                                                                                                                                     ^
2 errors generated.
make[1]: *** [CMakeFiles/cmTC_2d8fe.dir/HAVE_WINLDAP_H.c.obj] Error 1
make: *** [cmTC_2d8fe/fast] Error 2
exitCode: 2
```

Cherry-picked from #11095 88e4a21ff70ccef391cf99c8165281ff81374503
Reviewed-by: Daniel Stenberg
Closes #11245