GIT_CAP_THREADS
Libgit2 was compiled with thread support. Note that thread support is
still to be seen as a 'work in progress' - basic object lookups are
believed to be threadsafe, but other operations may not be.
GIT_CAP_HTTPS
Libgit2 supports the https:// protocol. This requires the openssl
library to be found when compiling libgit2.
