Makefiles: Re-implement makefile target path escaping and quoting

Previously we used `cmSystemTools::ConvertToOutputPath` which internally
used KWSys methods

* SystemTools::ConvertToUnixOutputPath
* SystemTools::ConvertToWindowsOutputPath

These were written in very early days of CMake and have some
limitations:

* They do not encode all characters.  E.g. '#' is left out.
* They attempt to do some path cleanup and handle existing quotes.
  These days CMake has clean unquoted paths already.
* They attempted to encode paths both for makefile targets and
  for shell command lines.  The latter use has mostly been replaced.
* Choosing between the two methods depends on a global variable!
  Several code paths in CMake have to copy the global generator's
  member ForceUnixPaths variable over to the cmSystemTools global.

Re-implement the `ConvertToMakefilePath` method to drop use of those
methods.  Compute suitable makefile target path escaping and quoting
via local logic.  Add support for more characters like '#'.

Fixes: #20555

Source/cmGlobalUnixMakefileGenerator3.cxx

@@ -486,17 +486,25 @@ void cmGlobalUnixMakefileGenerator3::WriteDirectoryRules2(
   }
 }
 
-std::string cmGlobalUnixMakefileGenerator3::ConvertToMakefilePath(
-  std::string const& path) const
+namespace {
+std::string ConvertToMakefilePathForUnix(std::string const& path)
 {
-  std::string const& out = cmSystemTools::ConvertToOutputPath(path);
   std::string result;
-  result.reserve(out.size());
-  for (char c : out) {
+  result.reserve(path.size());
+  for (char c : path) {
     switch (c) {
       case '=':
+        // We provide 'EQUALS = =' to encode '=' in a non-assignment case.
         result.append("$(EQUALS)");
         break;
+      case '$':
+        result.append("$$");
+        break;
+      case '\\':
+      case ' ':
+      case '#':
+        result.push_back('\\');
+        CM_FALLTHROUGH;
       default:
         result.push_back(c);
         break;
@@ -505,6 +513,51 @@ std::string cmGlobalUnixMakefileGenerator3::ConvertToMakefilePath(
   return result;
 }
 
+#if defined(_WIN32) && !defined(__CYGWIN__)
+std::string ConvertToMakefilePathForWindows(std::string const& path)
+{
+  bool const quote = path.find_first_of(" #") != std::string::npos;
+  std::string result;
+  result.reserve(path.size() + (quote ? 2 : 0));
+  if (quote) {
+    result.push_back('"');
+  }
+  for (char c : path) {
+    switch (c) {
+      case '=':
+        // We provide 'EQUALS = =' to encode '=' in a non-assignment case.
+        result.append("$(EQUALS)");
+        break;
+      case '$':
+        result.append("$$");
+        break;
+      case '/':
+        result.push_back('\\');
+        break;
+      default:
+        result.push_back(c);
+        break;
+    }
+  }
+  if (quote) {
+    result.push_back('"');
+  }
+  return result;
+}
+#endif
+}
+
+std::string cmGlobalUnixMakefileGenerator3::ConvertToMakefilePath(
+  std::string const& path) const
+{
+#if defined(_WIN32) && !defined(__CYGWIN__)
+  if (!this->ForceUnixPaths) {
+    return ConvertToMakefilePathForWindows(path);
+  }
+#endif
+  return ConvertToMakefilePathForUnix(path);
+}
+
 std::vector<cmGlobalGenerator::GeneratedMakeCommand>
 cmGlobalUnixMakefileGenerator3::GenerateBuildCommand(
   const std::string& makeProgram, const std::string& /*projectName*/,