fuzz: make hongfuzz fuzzing the default feature

This way you can run `cargo clippy --all` in the root, and `cargo hfuzz
run` without modification.

fuzz/Cargo.toml

@@ -9,6 +9,7 @@ publish = false
 cargo-fuzz = true
 
 [features]
+default = ["honggfuzz_fuzz"]
 afl_fuzz = ["afl"]
 honggfuzz_fuzz = ["honggfuzz"]
 

fuzz/generate-files.sh

@@ -20,6 +20,7 @@ publish = false
 cargo-fuzz = true
 
 [features]
+default = ["honggfuzz_fuzz"]
 afl_fuzz = ["afl"]
 honggfuzz_fuzz = ["honggfuzz"]