cranelift-fuzzgen-verify is redundant with cranelift-fuzzgen (#4411)

The compile step that cranelift-fuzzgen does also triggers IR
verification. So all bugs that cranelift-fuzzgen-verify could catch are
also caught by cranelift-fuzzgen. Removing redundant fuzzers lets us
spend limited fuzz-testing CPU time budgets better.

fuzz/fuzz_targets/cranelift-fuzzgen-verify.rs

@@ -1,11 +0,0 @@
-#![no_main]
-
-use libfuzzer_sys::fuzz_target;
-
-use cranelift_codegen::{settings, verify_function};
-use cranelift_fuzzgen::TestCase;
-
-fuzz_target!(|testcase: TestCase| {
-    let flags = settings::Flags::new(settings::builder());
-    verify_function(&testcase.func, &flags).unwrap();
-});