Revert previous linker additions for FreeBSD as the problem is Bazel using /usr/bin/clang instead of /usr/bin/clang++ to link C++ code. (#1035)

BUILD.bazel

@@ -2,35 +2,14 @@ load("@rules_cc//cc:defs.bzl", "cc_library")
 
 licenses(["notice"])
 
-config_setting(
-    name = "freebsd",
-    constraint_values = [
-        "@platforms//os:freebsd",
-    ],
-    visibility = [":__subpackages__"],
-)
-
-config_setting(
-    name = "openbsd",
-    constraint_values = [
-        "@platforms//os:openbsd",
-    ],
-    visibility = [":__subpackages__"],
-)
-
 config_setting(
     name = "windows",
-    constraint_values = [
-        "@platforms//os:windows",
-    ],
+    values = {
+        "cpu": "x64_windows",
+    },
     visibility = [":__subpackages__"],
 )
 
-BSD_LINKOPTS = [
-    "-pthread",
-    "-lm",
-]
-
 cc_library(
     name = "benchmark",
     srcs = glob(
@@ -43,8 +22,6 @@ cc_library(
     hdrs = ["include/benchmark/benchmark.h"],
     linkopts = select({
         ":windows": ["-DEFAULTLIB:shlwapi.lib"],
-        ":freebsd": BSD_LINKOPTS,
-        ":openbsd": BSD_LINKOPTS,
         "//conditions:default": ["-pthread"],
     }),
     strip_include_prefix = "include",

WORKSPACE

@@ -34,9 +34,3 @@ new_local_repository(
     build_file = "@//bindings/python:python_headers.BUILD",
     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"],
-)