Provide a "pypy3"-plugin project and make the PyPy-plugin compile properly on FreeBSD. Because pypy_setup.py needs to be properly included within the plugin binary the corresponding binary linking step has been changed to include an "-m" flag because on FreeBSD the current LLVM linker (ld.lld) obviously has no default setting. Per default it is derived from the first object file. But in the binary linking step there is no such .o file. It needs to be included within the uwsgi binary because it is neede to build the plugins when using the uwsgi binary with the "--build-plugin" option.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/uwsginl-plugin-lang-pypy3/pkg-descr	Sun Jun 14 20:03:33 2020 +0200
@@ -0,0 +1,5 @@
+PyPy3 language plugin for uwsginl.
+Dynymically Links to the default PyPy version on the system by default.
+Use --pypy-lib to link to libpypy3-c.so.
+
+WWW: https://projects.unbit.it/uwsgi/