Add symbols file
This adds a
libyaml-cpp0.6.symbols file, and infrastructure to generate a list of weak symbols included in it.
As yaml-cpp does not use
__attribute__ ((weak)) itself, the only source of weak symbols in the DSO are inline functions the compiler has chosen to emit a (weak) symbol for. This set of symbols is highly compiler and architecture specific, but fortunately applications linking to
libyaml-cpp.so.0.6 don't need those symbols anyway (as they've got their own inlined copy).
This symbols file works on all Ubuntu-supported architectures (amd64, armhf, aarch64, s390x, ppc64el), and should work on all Debian architectures, although I've not tested that.