Fix inconsistent symbol mangling with -Zverbose

Always skip arguments that are the defaults of their respective
parameters, to avoid generating inconsistent symbols for builds
with `-Zverbose` flag and without it.

compiler/rustc_middle/src/ty/print/mod.rs

@@ -188,11 +188,6 @@ pub trait Printer<'tcx>: Sized {
             own_params.start = 1;
         }
 
-        // If we're in verbose mode, then print default-equal args too
-        if self.tcx().sess.verbose() {
-            return &substs[own_params];
-        }
-
         // Don't print args that are the defaults of their respective parameters.
         own_params.end -= generics
             .params