This change:
* Builds the library with Go 1.14, too.
* Builds the non-legacy tests with Ubuntu Focal (20.04).
* Adds testing for system-wide libraries, both static and dynamic
versions.
* Fixes a typo in the README.
This change allows to link the system version of libgit2 statically.
Since `-tags static` is already used for the bundled version of the
library and to avoid breaking old workflows, `-tags
static,system_libgit2` is now used to select that.
This means that the valid combinations are:
| Flag | Effect |
|-------------------------------|-----------------------------------------------|
| _No flags_ | Dynamically-linked against the system libgit2 |
| `-tags static,system_libgit2` | Statically-linked against the system libgit2 |
| `-tags static` | Statically-linked against the bundled libgit2 |
Note that there is no way to express dynamically linking against the
bundled libgit2 because that makes very little sense, since the binaries
wouldn't be able to be distributed. If that's still desired, the
`PKG_CONFIG_PATH` environment variable can set before building the code.
[`Makefile`](https://github.com/libgit2/git2go/blob/master/Makefile) has
an example of how it is used in the CI.
CGO can perform variable substitution in the directives, so we don't
need to use a script to set up the variables; we can let the go tool do
it for us.
With the release of libgit2 v0.22 we can link against a version of
library we've wrapped in more than a PoC sense.
Explain the difference and say how to use each version.
lhchavez
Suhaib Mujahid
Carlos Martín Nieto
reujab
jbranchaud
Andreas Beer
Steven Wilkin
Amanpreet Singh
Bartosz Gęza
Vicent Marti