lookup_lib returns all the benchmarks from the specified library
val add_bench : name:string->code:string->filename:string->type_conv_path:string->line:int->startpos:int->endpos:int->Entry.test_spec-> unit
add_bench registers benchmarks with the global hashtable maintained in ppx_bench_lib. This is meant to be called by the code generated for the BENCH and BENCH_INDEXED macros
val add_bench_module : name:string->code:string->type_conv_path:string->filename:string->line:int->startpos:int->endpos:int->(unit -> unit)-> unit
add_bench_module adds a bench module name to the benchmarks. This is called by BENCH_MODULE macro