No need to set BenchmarkSet's @@current for load* methods

* It's already set by BenchmarkSet#initialize.

Author: eregon

bench/benchmark-interface/lib/benchmark-interface/benchmark-set.rb

@@ -20,19 +20,16 @@ def initialize
 
     def load_benchmarks(path)
       @path = path
-      @@current = self
       load(path)
     end
 
     def load_inlined_benchmark(code)
       @path = '-e'
-      @@current = self
       TOPLEVEL_BINDING.eval(code)
     end
 
     def load_mri_benchmarks(path, options)
       @path = path
-      @@current = self
       Frontends::MRI.load_mri path, options
     end