cmSystemTools: use the actual case for root detection

On Windows, calling a binary installed with the default `bin` binary
directory will fail to be detected when called as `BIN\cmake.exe` due to
the string compare. Get the actual case of the path before checking that
the path ends with `CMAKE_BIN_DIR`.

Fixes #16574.

Source/cmSystemTools.cxx

@@ -1979,7 +1979,8 @@ void cmSystemTools::FindCMakeResources(const char* argv0)
   // Install tree has
   // - "<prefix><CMAKE_BIN_DIR>/cmake"
   // - "<prefix><CMAKE_DATA_DIR>"
-  if (cmHasSuffix(exe_dir, CMAKE_BIN_DIR)) {
+  const std::string actual_case = cmSystemTools::GetActualCaseForPath(exe_dir);
+  if (cmHasSuffix(actual_case, CMAKE_BIN_DIR)) {
     std::string const prefix =
       exe_dir.substr(0, exe_dir.size() - strlen(CMAKE_BIN_DIR));
     cmSystemToolsCMakeRoot = prefix + CMAKE_DATA_DIR;