Adds -lm linker flag for FreeBSD/OpenBSD and uses github.com/bazelbuil… (#1032)

* Adds -lm linker flag for (Free|Open)BSD and uses github.com/bazelbuild/platforms for platform detection.

* Prefer selects.with_or to select the linkopts.

* @platforms appears to be implicitly available. @bazel_skylib would require updating every dependent repository.

* Re-enable platforms package.

1 files changed, 5 insertions, 0 deletions

diff --git a/WORKSPACE b/WORKSPACE
index 5438ad3..7f2612b 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -35,3 +35,8 @@ new_local_repository(
     path = "/usr/include/python3.6",  # May be overwritten by setup.py.
 )
 
+http_archive(
+    name = "platforms",
+    strip_prefix = "platforms-master",
+    urls = ["https://github.com/bazelbuild/platforms/archive/master.zip"],
+)