sh_configure.bzl: FreeBSD is also a known platform

Change-Id: I51ffe838d8c0e067f8e5ab3a6aef18e1ad063638
PiperOrigin-RevId: 196666303

tools/sh/sh_configure.bzl

diff --git a/tools/sh/sh_configure.bzl b/tools/sh/sh_configure.bzl
index 7ba056c..cfae327 100644
--- a/tools/sh/sh_configure.bzl
+++ b/tools/sh/sh_configure.bzl
@@ -56,6 +56,8 @@
     os_label = "@bazel_tools//platforms:linux"
   elif repository_ctx.os.name.startswith("mac"):
     os_label = "@bazel_tools//platforms:osx"
+  elif repository_ctx.os.name.startswith("freebsd"):
+    os_label = "@bazel_tools//platforms:freebsd"
   else:
     fail("Unknown OS")