运行 Casablanca 程序失败，在 Mac OS 上找不到“openssl/conf.h”文件

我正在尝试设置一个 Http 客户端并使用此处显示的示例下载一些数据。

当我尝试运行该程序时，它失败并提示未找到“conf.h”。

$g++ -std=c++11 BingSearch.cpp
In file included from BingSearch.cpp:1:
In file included from /usr/local/include/cpprest/http_client.h:53:
In file included from /usr/local/include/boost/asio/ssl.hpp:19:
In file included from /usr/local/include/boost/asio/ssl/context.hpp:27:
In file included from /usr/local/include/boost/asio/ssl/context_base.hpp:19:
/usr/local/include/boost/asio/ssl/detail/openssl_types.hpp:20:10: fatal error: 'openssl/conf.h' file not found
#include <openssl/conf.h>
         ^
1 error generated.

我查看了其他 SO帖子，并设置了必要的路径变量。

$echo $LDFLAGS
-L/usr/local/opt/openssl/lib
$echo $CPPFLAGS
-I/usr/local/opt/openssl/include
$echo $PKG_CONFIG_PATH
/usr/local/opt/openssl/lib/pkgconfig

conf.h 也位于 openssl 目录中

openssl $find /usr/local/opt/openssl/ -name "conf.h"
/usr/local/opt/openssl//include/openssl/conf.h

编译以下文件还需要做些什么吗？它是从这里得到的。

#include <cpprest/http_client.h>
#include <cpprest/filestream.h>

using namespace utility;                    // Common utilities like string conversions
using namespace web;                        // Common features like URIs.
using namespace web::http;                  // Common HTTP functionality
using namespace web::http::client;          // HTTP client features
using namespace concurrency::streams;       // Asynchronous streams

int main(int argc, char* argv[])
{
    auto fileStream = std::make_shared<ostream>();

    // Open stream to output file.
    pplx::task<void> requestTask = fstream::open_ostream(U("results.html")).then([=](ostream outFile)
            {
            *fileStream = outFile;

            // Create http_client to send the request.
            http_client client(U("http://www.bing.com/"));

            // Build request URI and start the request.
            uri_builder builder(U("/search"));
            builder.append_query(U("q"), U("cpprestsdk github"));
            return client.request(methods::GET, builder.to_string());
            })

    // Handle response headers arriving.
    .then([=](http_response response)
            {
            printf("Received response status code:%u\n", response.status_code());

            // Write response body into the file.
            return response.body().read_to_end(fileStream->streambuf());
            })

    // Close the file stream.
    .then([=](size_t)
            {
            return fileStream->close();
            });

    // Wait for all the outstanding I/O to complete and handle any exceptions
    try
    {
        requestTask.wait();
    }
    catch (const std::exception &e)
    {
        printf("Error exception:%s\n", e.what());
    }

    return 0;
}