Prevents
```
[ 168s] /home/abuild/rpmbuild/BUILD/reflective-rapidjson-1563638877.5f7c18b/lib/tests/jsonreflector.cpp:41:12: warning: type 'SomeEnumClass' violates the C++ One Definition Rule [-Wodr]
[ 168s] 41 | enum class SomeEnumClass {
[ 168s] | ^
[ 168s] /home/abuild/rpmbuild/BUILD/reflective-rapidjson-1563638877.5f7c18b/lib/tests/binaryreflector.cpp:39:12: note: a type with different precision is defined in another translation unit
[ 168s] 39 | enum class SomeEnumClass : std::uint16_t {
[ 168s] | ^
```
observed in LTO-enabled builds