add diesel-1.4.8 benchmark scaffolding

- empty [workspace]
- readme
- perf-config.json: `diesel` used to be a workspace with members, but we don't need to configure it in a special way now
- incremental patch

Author: lqd

collector/benchmarks/README.md

@@ -32,6 +32,10 @@ They mostly consist of real-world crates.
   ensure a lot of invariants. Stresses anything related to resolving
   trait bounds, by having a lot of trait impls for a large number of different
   types.
+- **diesel-1.4.8**: A type safe SQL query builder. Utilizes the type system to
+  ensure a lot of invariants. Stresses anything related to resolving
+  trait bounds, by having a lot of trait impls for a large number of different
+  types.
 - **helloworld**: A trivial program. Gives a lower bound on compile time.
 - **html5ever**: An HTML parser. Stresses macro parsing code significantly.
 - **hyper-2**: A fairly large crate. Utilizes async/await, and used by

collector/benchmarks/diesel-1.4.8/0-println.patch

@@ -0,0 +1,12 @@
+diff --git a/src/query_dsl/mod.rs b/src/query_dsl/mod.rs
+index 68c1cf74..1dcd513d 100644
+--- a/src/query_dsl/mod.rs
++++ b/src/query_dsl/mod.rs
+@@ -112,6 +112,7 @@ pub trait QueryDsl: Sized {
+     where
+         Self: methods::DistinctDsl,
+     {
++        println!("testing");
+         methods::DistinctDsl::distinct(self)
+     }
+ 

collector/benchmarks/diesel-1.4.8/Cargo.toml

@@ -136,3 +136,5 @@ with-deprecated = []
 x128-column-tables = ["128-column-tables"]
 x32-column-tables = ["32-column-tables"]
 x64-column-tables = ["64-column-tables"]
+
+[workspace]

collector/benchmarks/diesel-1.4.8/perf-config.json

@@ -0,0 +1,3 @@
+{
+  "category": "primary"
+}