Improvements to error reporting (#470)

* Fixed error reporting.

* Fixed compile time error when wasm feature is disabled.

* Fixed valid instructions not being printed in print_function_error.

* Fixed errors print_function_error not writing valid instructions after end.

* Made multiple checks non-fatal.

* verify_global_values is no longer fatal.

* Slightly better formatting of errors in pretty_verifier_error.

cranelift/src/clif-util.rs

@@ -21,12 +21,12 @@ extern crate serde_derive;
 #[cfg(feature = "disas")]
 extern crate capstone;
 extern crate pretty_env_logger;
-extern crate term;
 
 cfg_if! {
     if #[cfg(feature = "wasm")] {
         extern crate cranelift_entity;
         extern crate cranelift_wasm;
+        extern crate term;
         extern crate wabt;
         mod wasm;
     }