hadrian: Tell testsuite driver about LLVM availability

This reflects the logic present in the Make build system into Hadrian.

Fixes #18167.

hadrian/src/Settings/Builders/RunTest.hs

@@ -70,6 +70,7 @@ runTestBuilderArgs = builder RunTest ? do
     withSMP             <- getBooleanSetting TestGhcWithSMP
     debugged            <- getBooleanSetting TestGhcDebugged
     keepFiles           <- expr (testKeepFiles <$> userSetting defaultTestArgs)
+    withLlvm            <- expr (not . null <$> settingsFileSetting SettingsFileSetting_LlcCommand)
 
     accept <- expr (testAccept <$> userSetting defaultTestArgs)
     (acceptPlatform, acceptOS) <- expr . liftIO $
@@ -121,7 +122,7 @@ runTestBuilderArgs = builder RunTest ? do
             , arg "-e", arg $ asBool "config.have_dynamic="   (hasLibWay dynamic)
             , arg "-e", arg $ asBool "config.have_profiling=" (hasLibWay profiling)
             , arg "-e", arg $ asBool "ghc_with_smp=" withSMP
-            , arg "-e", arg $ "ghc_with_llvm=0" -- TODO: support LLVM
+            , arg "-e", arg $ asBool "ghc_with_llvm=" withLlvm
 
             , arg "-e", arg $ "config.ghc_dynamic_by_default=" ++ show hasDynamicByDefault
             , arg "-e", arg $ "config.ghc_dynamic=" ++ show hasDynamic