fix : remove _{ } syntax from benchmark macro (#7822)

* commented use of common

* hack to pass tests

* another hack

* remove all commented code

* fix the easy tests

* temp hack

* follow through comma hack until better solution

* patch macro

* missed one

* update benchmarks

* update docs

* fix docs

* removed too much

* fix changes

Co-authored-by: Shawn Tabrizi <shawntabrizi@gmail.com>

substrate/frame/system/benchmarking/src/lib.rs

@@ -38,8 +38,6 @@ pub struct Module<T: Config>(System<T>);
 pub trait Config: frame_system::Config {}
 
 benchmarks! {
-	_ { }
-
 	remark {
 		let b in 0 .. *T::BlockLength::get().max.get(DispatchClass::Normal) as u32;
 		let remark_message = vec![1; b as usize];