Remove dead ConvertPathList

Closes #4494.

PiperOrigin-RevId: 183380779
diff --git a/src/main/cpp/option_processor.cc b/src/main/cpp/option_processor.cc
index 4a6e579..89fcf2b 100644
--- a/src/main/cpp/option_processor.cc
+++ b/src/main/cpp/option_processor.cc
@@ -480,7 +480,7 @@
   if (pos == string::npos) return;
   string name = env_str->substr(0, pos);
   if (name == "PATH") {
-    env_str->assign("PATH=" + ConvertPathList(env_str->substr(pos + 1)));
+    env_str->assign("PATH=" + env_str->substr(pos + 1));
   } else if (name == "TMP") {
     // A valid Windows path "c:/foo" is also a valid Unix path list of
     // ["c", "/foo"] so must use ConvertPath here. See GitHub issue #1684.