fixup! Remove BinaryBuilder and fix tests on nightly

Author: JamesWrigley

test/test_bitfield.jl

@@ -1,3 +1,4 @@
+import Libdl: dlext
 import CMake_jll: cmake
 using Clang.Generators
 
@@ -47,8 +48,8 @@ function build_libbitfield()
         options["general"]["library_name"] = "\"$(escape_string(lib_path))\""
         options["general"]["output_file_path"] = output_path
 
-        run(`file $(lib_path)`)
-        run(`ldd $(lib_path)`)
+        run(`file $(lib_path).$(dlext)`)
+        run(`ldd $(lib_path).$(dlext)`)
 
         ctx = create_context(headers, args, options)
         build!(ctx)