Upstream libgit2 has migrated to use the GNUInstallDirs module to decide
where things will be installed to by default. While it improves
consistency with the host system, we're not really after that when
building the vendored libgit2 library, and in fact libgit2.{a,pc} may
now be installed into a different directory than before as it started to
depend on the host platform.
Fix this by explicitly specifying that we want the library and pkgconfig
file to be installed into a plain "lib/" directory.
This change removes the `LIB_INSTALL_DIR` and `INCLUDE_INSTALL_DIR` from
the `script/build-libgit2.sh` script, since they are now unneeded and
just print a warning if they are used.
This change:
* Updates the GitHub actions so that they run different commands for the
dynamic and static flavors of libgit2.
* Updates the .travis.yml file so that it does roughly the same as the
GitHub actions.
* Adds the release-* branches to the CI configurations.
Patrick Steinhardt
lhchavez
Carlos Martín Nieto