In more detail, what you are doing in your original code is testing the value of 5 different expressions:
1. wordChar == 'a'
Expressions 2 - 5 are always non-zero, and are therefore always true. The expression wordChar == 'a' || 'e' || 'i' || 'o' || 'u' is therefore always true.
And goto is something to be avoided, generally. Only use it if you really, really need to. And if you think you really, really need to, it's likely that you need to reconsider the design and structure of your code. In this case, it's utterly unnecessary - there are much better ways to force an early exit from a loop.