Fix "websocketpp" on Mac OS X.

[BYVoid]

This change fixes the build on Mac OS X. According to the original CMakeLists.txt, "rt" is not linked on Mac OS X.

    if (NOT APPLE)
        set (WEBSOCKETPP_PLATFORM_LIBS pthread rt)
    else()
        set (WEBSOCKETPP_PLATFORM_LIBS pthread)
    endif()

[bazel-io]

Hello @bazelbuild/bcr-maintainers, modules without existing maintainers (websocketpp) have been updated in this PR. Please review the changes.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[Wyverald]

Existing versions cannot be changed on BCR. Please create a new version with a .bcr.<N> suffix (so 0.8.2.bcr.1 here).

[BYVoid]

Created 0.8.2.bcr.1 instead.

[meteorcloudy]

Please add the new version to https://github.com/bazelbuild/bazel-central-registry/blob/main/modules/websocketpp/metadata.json#L13

[meteorcloudy]

@carbo-asr And can you please sign the Google CLA.

[BYVoid]

"All contributors are covered under a CLA with Google".

[meteorcloudy]

Please fix

BcrValidationResult.FAILED: The patch file `modules/websocketpp/0.8.2.bcr.1/patches/add_build_file.patch` has expected integrity value `sha256-KhVOfO47POB3xqoHdeOs+dYbn0dp0aAQddYt8ZWZqcI=`, but the real integrity value is `sha256-95DACIWxqhjix5VgVssEYee5pjCnf/QWL04mQJwQ2uM=`.
patching file BUILD.bazel
BcrValidationResult.FAILED: The patch file `modules/websocketpp/0.8.2.bcr.1/patches/module_dot_bazel.patch` has expected integrity value `sha256-Bq9+2iYvtN8TR5zGaKTIdS3vYsx/gEP0pM2xLWuMO2U=`, but the real integrity value is `sha256-h9esq/BSgla/GaK2cdr7QK71dXvYWj64udsLV06S180=`.