Revert "Disable LLVM post processing (#2626)"

This reverts commit eff7b30.

Author: alexbaden

third_party/intel/backend/compiler.py

@@ -298,7 +298,7 @@ def make_llir(src, metadata, options):
             paths = [path for (name, path) in options.extern_libs]
             llvm.link_extern_libs(llvm_mod, paths)
         intel.optimize_module(llvm_mod, llvm.OPTIMIZE_O3)
-        if os.getenv("TRITON_INTEL_ENABLE_POST_PROCESS_LLIR", "0") == "1":
+        if os.getenv("TRITON_INTEL_ENABLE_POST_PROCESS_LLIR", "1") == "1":
             intel.post_process_llir(llvm_mod)
 
         # Get some metadata