use build flag instead

Author: xiazhvera

source/connection.c

@@ -1058,10 +1058,12 @@ int aws_http_client_connect_internal(
         return aws_raise_error(AWS_ERROR_INVALID_ARGUMENT);
     }
 
-    if (aws_is_using_secitem() && proxy_request_transform) {
-        AWS_LOGF_ERROR(AWS_LS_HTTP_PROXY_NEGOTIATION, "HTTP proxy is not supported with Apple Network Framework.");
+#if defined(AWS_USE_SECITEM) && defined(AWS_OS_APPLE)
+    if (proxy_request_transform) {
+        AWS_LOGF_ERROR(AWS_LS_HTTP_PROXY_NEGOTIATION, "HTTP proxy is not supported on Apple Network Framework.");
         return aws_raise_error(AWS_ERROR_PLATFORM_NOT_SUPPORTED);
     }
+#endif
 
     struct aws_http_client_bootstrap *http_bootstrap = NULL;
     struct aws_string *host_name = NULL;

source/proxy_connection.c

@@ -9,6 +9,7 @@
 #include <aws/common/encoding.h>
 #include <aws/common/environment.h>
 #include <aws/common/hash_table.h>
+#include <aws/common/platform.h>
 #include <aws/common/string.h>
 #include <aws/http/connection_manager.h>
 #include <aws/http/private/connection_impl.h>
@@ -1565,10 +1566,12 @@ int aws_http_options_validate_proxy_configuration(const struct aws_http_client_c
         return aws_raise_error(AWS_ERROR_INVALID_ARGUMENT);
     }
 
-    if (aws_is_using_secitem() && (options->proxy_options || options->proxy_ev_settings)) {
-        AWS_LOGF_ERROR(AWS_LS_HTTP_PROXY_NEGOTIATION, "HTTP proxy is not supported with Apple Network Framework.");
+#if defined(AWS_USE_SECITEM) && defined(AWS_OS_APPLE)
+    if ((options->proxy_options || options->proxy_ev_settings)) {
+        AWS_LOGF_ERROR(AWS_LS_HTTP_PROXY_NEGOTIATION, "HTTP proxy is not supported on Apple Network Framework.");
         return aws_raise_error(AWS_ERROR_PLATFORM_NOT_SUPPORTED);
     }
+#endif
 
     enum aws_http_proxy_connection_type proxy_type = options->proxy_options->connection_type;
     if (proxy_type == AWS_HPCT_HTTP_FORWARD && options->tls_options != NULL) {