libcurl employs some typechecking via "curl/typecheck-gcc.h". When
compling with --enable-lto, compilation fails otherwise with:

    make[2]: Entering directory '/data/src/NetworkManager'
      CC       src/src_libNetworkManager_la-nm-connectivity.lo
      CCLD     src/libNetworkManager.la
      CCLD     src/libNetworkManagerTest.la
      CCLD     src/dhcp/tests/test-dhcp-dhclient
    src/nm-connectivity.c: In function 'curl_check_connectivity':
    src/nm-connectivity.c:147:10: error: call to '_curl_easy_getinfo_err_string' declared with attribute warning: curl_easy_getinfo expects a pointer to char * for this info [-Werror]
       eret = curl_easy_getinfo (msg->easy_handle, CURLINFO_PRIVATE, &cb_data);
              ^
    lto1: all warnings being treated as errors
    lto-wrapper: fatal error: /usr/bin/gcc returned 1 exit status
    compilation terminated.
    /usr/bin/ld: error: lto-wrapper failed