Fix main ut tests when not using libcurl (#1227)

* Fix for test cases when not using libcurl

sdk/core/azure-core/test/ut/main.cpp

@@ -1,14 +1,23 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // SPDX-License-Identifier: MIT
 
-#include <curl/curl.h>
 #include <gtest/gtest.h>
 
+#if defined(BUILD_CURL_HTTP_TRANSPORT_ADAPTER)
+#include <curl/curl.h>
+#endif
+
 int main(int argc, char** argv)
 {
+#if defined(BUILD_CURL_HTTP_TRANSPORT_ADAPTER)
   curl_global_init(CURL_GLOBAL_ALL);
+#endif
+
   testing::InitGoogleTest(&argc, argv);
   auto r = RUN_ALL_TESTS();
+
+#if defined(BUILD_CURL_HTTP_TRANSPORT_ADAPTER)
   curl_global_cleanup();
+#endif
   return r;
 }