[fuzz] Rename differential_meta to differential

Now that the `differential_meta` fuzz target does everything that the
existing `differential` target did and more, it can take over the
original name.

fuzz/Cargo.toml

@@ -55,8 +55,8 @@ test = false
 doc = false
 
 [[bin]]
-name = "differential_meta"
-path = "fuzz_targets/differential_meta.rs"
+name = "differential"
+path = "fuzz_targets/differential.rs"
 test = false
 doc = false
 

fuzz/README.md

@@ -34,7 +34,7 @@ At the time of writing, we have the following fuzz targets:
   to its source, yielding a function A', and checks that A compiled +
   incremental compilation generates the same machine code as if A' was compiled
   from scratch.
-* `differential_meta`: Generate a Wasm module, evaluate each exported function
+* `differential`: Generate a Wasm module, evaluate each exported function
   with random inputs, and check that Wasmtime returns the same results as a
   choice of another engine: the Wasm spec interpreter (see the
   `wasm-spec-interpreter` crate), the `wasmi` interpreter, or Wasmtime itself