update hunter version to use a newer opentracing-cpp?

[ppggff]

The build-in version hunter will build with opentracing-cpp 1.4.0, and the "plugin so" will return error with other version.

[isaachier]

Good catch. Will update now. Thanks.

[isaachier]

@rnburn, while doing this, discovered that Jaeger does not implement new OpenTracing dynamic loading function. Where do I use OPENTRACING_DECLARE_IMPL_FACTORY? In the implementation file (DynamicLoad.cpp) or in the tracer factory header (TracerFactory.h)?

[rnburn]

Yes, in the implementation file. It was added to support building on windows.

@mdouaihy updated it as part of his PR. You can see https://github.com/mdouaihy/jaeger-client-cpp/blob/9091fc42ed356cd51e640c039623279e0a4de761/src/jaegertracing/DynamicLoad.cpp

[ppggff]

It would be better to add the version number of corresponding opentracing-cpp with the released binary plugin library file.

[isaachier]

Fixed in #120.