libnghttp2.so was missing -fvisibility=hidden. libnghttp2_asio.so on the
other hand had hidden visibility which resulted in no exported symbols
and a broken asio client examples.
Just build a static nghttp2 library to solve this issue.
Split the nghttp2 library into objects and a shared library from those
objects. This is needed because of symbol visibility. An advantage over
the autotools build is that there are no worries about static versus
static library builds.
Test:
cmake $srcdir
make nghttpx-unittest main failmalloc
make test
Peter Wu