Modify "linkopts" for "websocketpp" depending on the operating system.

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()

modules/websocketpp/0.8.2/MODULE.bazel

@@ -6,3 +6,4 @@ module(
 bazel_dep(name = "asio", version = "1.28.2")
 bazel_dep(name = "rules_cc", version = "0.0.9")
 bazel_dep(name = "zlib", version = "1.3")
+bazel_dep(name = "platforms", version = "0.0.10")

modules/websocketpp/0.8.2/patches/add_build_file.patch

@@ -1,6 +1,6 @@
 --- /dev/null
 +++ BUILD.bazel
-@@ -0,0 +1,20 @@
+@@ -0,0 +1,25 @@
 +load("@rules_cc//cc:defs.bzl", "cc_library")
 +
 +cc_library(
@@ -11,10 +11,15 @@
 +        "_WEBSOCKETPP_CPP11_STL_",
 +    ],
 +    includes = ["."],
-+    linkopts = [
-+        "-lpthread",
-+        "-lrt",
-+    ],
++    linkopts = select({
++        "@platforms//os:osx": [
++            "-lpthread",
++        ],
++        "//conditions:default": [
++            "-lpthread",
++            "-lrt",
++        ],
++    }),
 +    visibility = ["//visibility:public"],
 +    deps = [
 +        "@asio",

modules/websocketpp/0.8.2/patches/module_dot_bazel.patch

@@ -1,6 +1,6 @@
 --- /dev/null
 +++ MODULE.bazel
-@@ -0,0 +1,8 @@
+@@ -0,0 +1,9 @@
 +module(
 +    name = "websocketpp",
 +    version = "0.8.2",
@@ -9,3 +9,4 @@
 +bazel_dep(name = "asio", version = "1.28.2")
 +bazel_dep(name = "rules_cc", version = "0.0.9")
 +bazel_dep(name = "zlib", version = "1.3")
++bazel_dep(name = "platforms", version = "0.0.10")