I'm using given conan packages

```
gtest/1.8.0@bincrafters/stable
boost/1.66.0@conan/stable
log4cplus/2.0.2@bincrafters/stable`

```

and clang (version at least 6.0).   

While first two packages has binaries for clang 6.0, log4cplus doesn't (last is clang 3.9). I don't like the idea that on each workstation I would need to build this package by hand.

How can I upload localy build binary with clang 6.0?  

`conan upload` looks promising, however it suggest that it will be NEW package.   
Second question - wouldn't I interfere with package author in any way?