Fix building zot natively on FreeBSD (#3247)

fix: allow zot to build on a FreeBSD host (#3246)

The build works as long as the protoc package is installed on the build
host. This also fixes lint checks when building on FreeBSD, working
around common lint complaints caused by the fact that rlim_t is int64 on
FreeBSD.

Signed-off-by: Doug Rabson <dfr@rabson.org>

pkg/test/common/rlimit_freebsd.go

@@ -0,0 +1,3 @@
+package common
+
+type RlimT = int64

pkg/test/common/rlimit_linux.go

@@ -0,0 +1,3 @@
+package common
+
+type RlimT = uint64