[dexter] Remove unused env vars from lit.cfg.py (llvm#150031)

I believe these are relics from the days of dexter having the ability to
build your code

Author: OCHyams

cross-project-tests/lit.cfg.py

@@ -237,15 +237,6 @@ def can_target_host():
     dependencies = configure_dexter_substitutions()
     if all(d in config.available_features for d in dependencies):
         config.available_features.add("dexter")
-        llvm_config.with_environment(
-            "PATHTOCLANG", add_host_triple(llvm_config.config.clang)
-        )
-        llvm_config.with_environment(
-            "PATHTOCLANGPP", add_host_triple(llvm_config.use_llvm_tool("clang++"))
-        )
-        llvm_config.with_environment(
-            "PATHTOCLANGCL", add_host_triple(llvm_config.use_llvm_tool("clang-cl"))
-        )
 else:
     print(
         "Host triple {} not supported. Skipping dexter tests in the "