C style casts in C++ code

[Karl Vestin]

The Codacy static code analysis reports several instances of C style casts in C++ code. This does probably not cause any actual problems in the field, but explicit C++ casts are better practise.

Codacy link: https://app.codacy.com/gh/epics-base/epics-base/issues?bid=16430872&filters=W3siaWQiOiJMYW5ndWFnZSIsInZhbHVlcyI6W119LHsiaWQiOiJDYXRlZ29yeSIsInZhbHVlcyI6W119LHsiaWQiOiJMZXZlbCIsInZhbHVlcyI6W119LHsiaWQiOiJQYXR0ZXJuIiwidmFsdWVzIjpbIjIxMzIiXX0seyJpZCI6IkF1dGhvciIsInZhbHVlcyI6W119XQ==