Expression evaluation for `void` valued expressions sets an error using the `kNoResult`
code. Like the `expression` command, `dwim-print` should also not print such errors.
Before:
```
(lldb) dwim-print (void)printf("hi\n")
hi
Error: 'unknown error'
```
After:
```
(lldb) dwim-print (void)printf("hi\n")
hi
```
rdar://109746544
Differential Revision: https://reviews.llvm.org/D151351