hadrian: build C/C++ with split sections when enabled

When split sections is enabled, ensure -fsplit-sections is passed to
GHC as well when invoking GHC to compile C/C++; and pass
-ffunction-sections -fdata-sections to gcc/clang when compiling C/C++
with the hadrian Cc builder. Fixes #23381.

hadrian/src/Settings/Builders/SplitSections.hs

@@ -29,6 +29,9 @@ splitSectionsArgs = do
     ) then
     ( mconcat
         [ builder (Ghc CompileHs) ? arg "-fsplit-sections"
+        , builder (Ghc CompileCWithGhc) ? arg "-fsplit-sections"
+        , builder (Ghc CompileCppWithGhc) ? arg "-fsplit-sections"
+        , builder (Cc CompileC) ? arg "-ffunction-sections" <> arg "-fdata-sections"
         , builder MergeObjects ? ifM (expr isWinTarget)
             (pure ["-T", "driver/utils/merge_sections_pe.ld"])
             (pure ["-T", "driver/utils/merge_sections.ld"])