use bumpptr in loop benchmark

src/benchmarks/loop.py

+from src.allocator import bumpptr
 from src.benchmark import Benchmark
 
 
@@ -15,6 +16,9 @@ class Benchmark_Loop(Benchmark):
         self.requirements = ["loop"]
         super().__init__()
 
+        # add bumpptr alloc
+        self.allocators["bumpptr"] = bumpptr.build()
+
     def summary(self):
         # Speed
         self.plot_fixed_arg("perm.nthreads / ({task-clock}/1000)",