gplugin/gplugin

Python3 has started shipping multiple pc files so we need to check for all of them similar to lua.

2021-07-23, Gary Kramlich
bf9af95cb6d4
Python3 has started shipping multiple pc files so we need to check for all of them similar to lua.

Testing Done:
Ran on debian unstable with python3.10 and python3.9 installed. pygobject doesn't current work with python3.10 according to the test output but python3.9 worked fine.

```
Dependency pygobject-3.0 found: YES 3.38.0 (cached)
Found pkg-config: /usr/bin/pkg-config (0.29.2)
Run-time dependency python-3.10-embed found: YES 3.10
Checking if "Python3 GI" with dependencies glib-2.0, python-3.10-embed, pygobject-3.0 runs: NO (255)
Message: pygobject does not work with python-3.10-embed
Run-time dependency python-3.9-embed found: YES 3.9
Checking if "Python3 GI" with dependencies glib-2.0, python-3.9-embed, pygobject-3.0 runs: YES
```

Reviewed at https://reviews.imfreedom.org/r/832/
There are a few notes about building on OSX.
First off, building has *ONLY* been tested against homebrew. If you want to
support fink or macports, please let me know and I will merge your pull
request.
Currently there is no known way to build the Perl loader on MacOS. So you
**MUST** run meson with `-Dperl5=false`.
## Lua
For the Lua loader to work, you need to install `lgi` from luarocks either
systemwide for lua 5.1 as `lgi` does not currently work with lua 5.4 which is
the default in homebrew.
To make this work, you'll need to install both `lua@5.1` and `luarocks` via
`brew install lua@5.1 luarocks`. Once those are installed, you'll need to
create `/usr/local/etc/luarocks/config-5.1.lua` with the following contents.
```
-- LuaRocks configuration
rocks_trees = {
{ name = "user", root = home .. "/.luarocks" };
{ name = "system", root = "/usr/local" };
}
lua_interpreter = "lua5.1";
variables = {
LUA_DIR = "/usr/local/opt/lua@5.1";
LUA_BINDIR = "/usr/local/opt/lua@5.1/bin";
}
```
Once that is done, you can then finally install `lgi` with the following
command.
```
luarocks --lua-version=5.1 install lgi
```
## Python3
If you're using homebrew, you need to install `pygobject3`.